signer: change the stdio jsonrpc to use legacy namespace conventions (#19047)

This PR will will break existing UIs, since it changes all calls like ApproveSignTransaction to be on the form ui_approveSignTransaction.

This is to make it possible for the UI to reuse the json-rpc library from go-ethereum, which uses this convention.

Also, this PR removes some unused structs, after import/export were removed from the external api (so no longer needs internal methods for approval)

One more breaking change is introduced, removing passwords from the ApproveSignTxResponse and the likes. This makes the manual interface more like the rulebased interface, and integrates nicely with the credential storage. Thus, the way it worked before, it would be tempting for the UI to implement 'remember password' functionality. The way it is now, it will be easy instead to tell clef to store passwords and use them.

If a pw is not found in the credential store, the user is prompted to provide the password.

cmd/clef/README.md

@@ -661,7 +661,7 @@ OBS! A slight deviation from `json` standard is in place: every request and resp
 Whereas the `json` specification allows for linebreaks, linebreaks __should not__ be used in this communication channel, to make
 things simpler for both parties.
 
-### ApproveTx
+### ApproveTx / `ui_approveTx`
 
 Invoked when there's a transaction for approval.
 
@@ -673,13 +673,13 @@ Here's a method invocation:
 
 curl -i -H "Content-Type: application/json" -X POST --data '{"jsonrpc":"2.0","method":"account_signTransaction","params":[{"from":"0x694267f14675d7e1b9494fd8d72fefe1755710fa","gas":"0x333","gasPrice":"0x1","nonce":"0x0","to":"0x07a565b7ed7d7a678680a4c162885bedbb695fe0", "value":"0x0", "data":"0x4401a6e40000000000000000000000000000000000000000000000000000000000000012"},"safeSend(address)"],"id":67}' http://localhost:8550/
 ```
-
+Results in the following invocation on the UI:
 ```json
 
 {
   "jsonrpc": "2.0",
   "id": 1,
-  "method": "ApproveTx",
+  "method": "ui_approveTx",
   "params": [
     {
       "transaction": {
@@ -724,7 +724,7 @@ curl -i -H "Content-Type: application/json" -X POST --data '{"jsonrpc":"2.0","me
 {
   "jsonrpc": "2.0",
   "id": 1,
-  "method": "ApproveTx",
+  "method": "ui_approveTx",
   "params": [
     {
       "transaction": {
@@ -767,7 +767,7 @@ One which has missing `to`, but with no `data`:
 {
   "jsonrpc": "2.0",
   "id": 3,
-  "method": "ApproveTx",
+  "method": "ui_approveTx",
   "params": [
     {
       "transaction": {
@@ -796,33 +796,7 @@ One which has missing `to`, but with no `data`:
 }
 ```
 
-### ApproveExport
-
-Invoked when a request to export an account has been made.
-
-#### Sample call
-
-```json
-
-{
-  "jsonrpc": "2.0",
-  "id": 7,
-  "method": "ApproveExport",
-  "params": [
-    {
-      "address": "0x0000000000000000000000000000000000000000",
-      "meta": {
-        "remote": "signer binary",
-        "local": "main",
-        "scheme": "in-proc"
-      }
-    }
-  ]
-}
-
-```
-
-### ApproveListing
+### ApproveListing / `ui_approveListing`
 
 Invoked when a request for account listing has been made.
 
@@ -833,7 +807,7 @@ Invoked when a request for account listing has been made.
 {
   "jsonrpc": "2.0",
   "id": 5,
-  "method": "ApproveListing",
+  "method": "ui_approveListing",
   "params": [
     {
       "accounts": [
@@ -860,7 +834,7 @@ Invoked when a request for account listing has been made.
 ```
 
 
-### ApproveSignData
+### ApproveSignData / `ui_approveSignData`
 
 #### Sample call
 
@@ -868,7 +842,7 @@ Invoked when a request for account listing has been made.
 {
   "jsonrpc": "2.0",
   "id": 4,
-  "method": "ApproveSignData",
+  "method": "ui_approveSignData",
   "params": [
     {
       "address": "0x123409812340981234098123409812deadbeef42",
@@ -886,7 +860,7 @@ Invoked when a request for account listing has been made.
 
 ```
 
-### ShowInfo
+### ShowInfo / `ui_showInfo`
 
 The UI should show the info to the user. Does not expect response.
 
@@ -896,7 +870,7 @@ The UI should show the info to the user. Does not expect response.
 {
   "jsonrpc": "2.0",
   "id": 9,
-  "method": "ShowInfo",
+  "method": "ui_showInfo",
   "params": [
     {
       "text": "Tests completed"
@@ -906,7 +880,7 @@ The UI should show the info to the user. Does not expect response.
 
 ```
 
-### ShowError
+### ShowError / `ui_showError`
 
 The UI should show the info to the user. Does not expect response.
 
@@ -925,7 +899,7 @@ The UI should show the info to the user. Does not expect response.
 
 ```
 
-### OnApproved
+### OnApprovedTx / `ui_onApprovedTx`
 
 `OnApprovedTx` is called when a transaction has been approved and signed. The call contains the return value that will be sent to the external caller.  The return value from this method is ignored - the reason for having this callback is to allow the ruleset to keep track of approved transactions.
 
@@ -933,7 +907,7 @@ When implementing rate-limited rules, this callback should be used.
 
 TLDR; Use this method to keep track of signed transactions, instead of using the data in `ApproveTx`.
 
-### OnSignerStartup
+### OnSignerStartup / `ui_onSignerStartup`
 
 This method provide the UI with information about what API version the signer uses (both internal and external) aswell as build-info and external api,
 in k/v-form.
@@ -944,7 +918,7 @@ Example call:
 {
   "jsonrpc": "2.0",
   "id": 1,
-  "method": "OnSignerStartup",
+  "method": "ui_onSignerStartup",
   "params": [
     {
       "info": {