les, light: LES/2 protocol version (#14970)

This PR implements the new LES protocol version extensions:

* new and more efficient Merkle proofs reply format (when replying to
  a multiple Merkle proofs request, we just send a single set of trie
  nodes containing all necessary nodes)
* BBT (BloomBitsTrie) works similarly to the existing CHT and contains
  the bloombits search data to speed up log searches
* GetTxStatusMsg returns the inclusion position or the
  pending/queued/unknown state of a transaction referenced by hash
* an optional signature of new block data (number/hash/td) can be
  included in AnnounceMsg to provide an option for "very light
  clients" (mobile/embedded devices) to skip expensive Ethash check
  and accept multiple signatures of somewhat trusted servers (still a
  lot better than trusting a single server completely and retrieving
  everything through RPC). The new client mode is not implemented in
  this PR, just the protocol extension.

eth/filters/filter.go

@@ -19,7 +19,6 @@ package filters
 import (
 	"context"
 	"math/big"
-	"time"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
@@ -136,11 +135,11 @@ func (f *Filter) indexedLogs(ctx context.Context, end uint64) ([]*types.Log, err
 	// Create a matcher session and request servicing from the backend
 	matches := make(chan uint64, 64)
 
-	session, err := f.matcher.Start(uint64(f.begin), end, matches)
+	session, err := f.matcher.Start(ctx, uint64(f.begin), end, matches)
 	if err != nil {
 		return nil, err
 	}
-	defer session.Close(time.Second)
+	defer session.Close()
 
 	f.backend.ServiceFilter(ctx, session)
 
@@ -152,9 +151,13 @@ func (f *Filter) indexedLogs(ctx context.Context, end uint64) ([]*types.Log, err
 		case number, ok := <-matches:
 			// Abort if all matches have been fulfilled
 			if !ok {
-				f.begin = int64(end) + 1
-				return logs, nil
+				err := session.Error()
+				if err == nil {
+					f.begin = int64(end) + 1
+				}
+				return logs, err
 			}
+			f.begin = int64(number) + 1
 			// Retrieve the suggested block and pull any truly matching logs
 			header, err := f.backend.HeaderByNumber(ctx, rpc.BlockNumber(number))
 			if header == nil || err != nil {