swarm: ctx propagation; bmt fixes; pss generic notification framework (#17150)

* cmd/swarm: minor cli flag text adjustments

* swarm/api/http: sticky footer for swarm landing page using flex

* swarm/api/http: sticky footer for error pages and fix for multiple choices

* cmd/swarm, swarm/storage, swarm: fix  mingw on windows test issues

* cmd/swarm: update description of swarm cmd

* swarm: added network ID test

* cmd/swarm: support for smoke tests on the production swarm cluster

* cmd/swarm/swarm-smoke: simplify cluster logic as per suggestion

* swarm: propagate ctx to internal apis (#754)

* swarm/metrics: collect disk measurements

* swarm/bmt: fix io.Writer interface

  * Write now tolerates arbitrary variable buffers
  * added variable buffer tests
  * Write loop and finalise optimisation
  * refactor / rename
  * add tests for empty input

* swarm/pss: (UPDATE) Generic notifications package (#744)

swarm/pss: Generic package for creating pss notification svcs

* swarm: Adding context to more functions

* swarm/api: change colour of landing page in templates

* swarm/api: change landing page to react to enter keypress

cmd/swarm/main.go

@@ -143,7 +143,7 @@ var (
 	}
 	SwarmWantManifestFlag = cli.BoolTFlag{
 		Name:  "manifest",
-		Usage: "Automatic manifest upload",
+		Usage: "Automatic manifest upload (default true)",
 	}
 	SwarmUploadDefaultPath = cli.StringFlag{
 		Name:  "defaultpath",
@@ -155,7 +155,7 @@ var (
 	}
 	SwarmUploadMimeType = cli.StringFlag{
 		Name:  "mime",
-		Usage: "force mime type",
+		Usage: "Manually specify MIME type",
 	}
 	SwarmEncryptedFlag = cli.BoolFlag{
 		Name:  "encrypt",