all: more linters (#24783)

This enables the following linters

- typecheck
- unused
- staticcheck
- bidichk
- durationcheck
- exportloopref
- gosec

WIth a few exceptions.

- We use a deprecated protobuf in trezor. I didn't want to mess with that, since I cannot meaningfully test any changes there.
- The deprecated TypeMux is used in a few places still, so the warning for it is silenced for now.
- Using string type in context.WithValue is apparently wrong, one should use a custom type, to prevent collisions between different places in the hierarchy of callers. That should be fixed at some point, but may require some attention.
- The warnings for using weak random generator are squashed, since we use a lot of random without need for cryptographic guarantees.

crypto/blake2b/blake2b.go

@@ -302,6 +302,7 @@ func appendUint64(b []byte, x uint64) []byte {
 	return append(b, a[:]...)
 }
 
+//nolint:unused,deadcode
 func appendUint32(b []byte, x uint32) []byte {
 	var a [4]byte
 	binary.BigEndian.PutUint32(a[:], x)
@@ -313,6 +314,7 @@ func consumeUint64(b []byte) ([]byte, uint64) {
 	return b[8:], x
 }
 
+//nolint:unused,deadcode
 func consumeUint32(b []byte) ([]byte, uint32) {
 	x := binary.BigEndian.Uint32(b)
 	return b[4:], x

crypto/blake2b/blake2b_generic.go

@@ -25,6 +25,7 @@ var precomputed = [10][16]byte{
 	{10, 8, 7, 1, 2, 4, 6, 5, 15, 9, 3, 13, 11, 14, 12, 0},
 }
 
+// nolint:unused,deadcode
 func hashBlocksGeneric(h *[8]uint64, c *[2]uint64, flag uint64, blocks []byte) {
 	var m [16]uint64
 	c0, c1 := c[0], c[1]

crypto/blake2b/blake2b_test.go

@@ -14,14 +14,6 @@ import (
 	"testing"
 )
 
-func fromHex(s string) []byte {
-	b, err := hex.DecodeString(s)
-	if err != nil {
-		panic(err)
-	}
-	return b
-}
-
 func TestHashes(t *testing.T) {
 	defer func(sse4, avx, avx2 bool) {
 		useSSE4, useAVX, useAVX2 = sse4, avx, avx2

crypto/bn256/cloudflare/gfp_decl.go

@@ -10,7 +10,7 @@ import (
 	"golang.org/x/sys/cpu"
 )
 
-//nolint:varcheck
+//nolint:varcheck,unused,deadcode
 var hasBMI2 = cpu.X86.HasBMI2
 
 // go:noescape