build: upgrade to go 1.19 (#25726)

This changes the CI / release builds to use the latest Go version. It also
upgrades golangci-lint to a newer version compatible with Go 1.19.

In Go 1.19, godoc has gained official support for links and lists. The
syntax for code blocks in doc comments has changed and now requires a
leading tab character. gofmt adapts comments to the new syntax
automatically, so there are a lot of comment re-formatting changes in this
PR. We need to apply the new format in order to pass the CI lint stage with
Go 1.19.

With the linter upgrade, I have decided to disable 'gosec' - it produces
too many false-positive warnings. The 'deadcode' and 'varcheck' linters
have also been removed because golangci-lint warns about them being
unmaintained. 'unused' provides similar coverage and we already have it
enabled, so we don't lose much with this change.

common/hexutil/hexutil.go

@@ -18,7 +18,7 @@
 Package hexutil implements hex encoding with 0x prefix.
 This encoding is used by the Ethereum RPC API to transport binary data in JSON payloads.
 
-Encoding Rules
+# Encoding Rules
 
 All hex data must have prefix "0x".
 

common/math/big.go

@@ -227,10 +227,10 @@ func U256Bytes(n *big.Int) []byte {
 // S256 interprets x as a two's complement number.
 // x must not exceed 256 bits (the result is undefined if it does) and is not modified.
 //
-//   S256(0)        = 0
-//   S256(1)        = 1
-//   S256(2**255)   = -2**255
-//   S256(2**256-1) = -1
+//	S256(0)        = 0
+//	S256(1)        = 1
+//	S256(2**255)   = -2**255
+//	S256(2**256-1) = -1
 func S256(x *big.Int) *big.Int {
 	if x.Cmp(tt255) < 0 {
 		return x

common/prque/lazyqueue.go

@@ -26,9 +26,10 @@ import (
 // LazyQueue is a priority queue data structure where priorities can change over
 // time and are only evaluated on demand.
 // Two callbacks are required:
-// - priority evaluates the actual priority of an item
-// - maxPriority gives an upper estimate for the priority in any moment between
-//   now and the given absolute time
+//   - priority evaluates the actual priority of an item
+//   - maxPriority gives an upper estimate for the priority in any moment between
+//     now and the given absolute time
+//
 // If the upper estimate is exceeded then Update should be called for that item.
 // A global Refresh function should also be called periodically.
 type LazyQueue struct {