all: replace log15 with slog (#28187)

This PR replaces Geth's logger package (a fork of [log15](https://github.com/inconshreveable/log15)) with an implementation using slog, a logging library included as part of the Go standard library as of Go1.21.

Main changes are as follows:
* removes any log handlers that were unused in the Geth codebase.
* Json, logfmt, and terminal formatters are now slog handlers.
* Verbosity level constants are changed to match slog constant values.  Internal translation is done to make this opaque to the user and backwards compatible with existing `--verbosity` and `--vmodule` options.
* `--log.backtraceat` and `--log.debug` are removed.

The external-facing API is largely the same as the existing Geth logger.  Logger method signatures remain unchanged.

A small semantic difference is that a `Handler` can only be set once per `Logger` and not changed dynamically.  This just means that a new logger must be instantiated every time the handler of the root logger is changed.

----
For users of the `go-ethereum/log` module. If you were using this module for your own project, you will need to change the initialization. If you previously did 
```golang
log.Root().SetHandler(log.LvlFilterHandler(log.LvlInfo, log.StreamHandler(os.Stderr, log.TerminalFormat(true))))
```
You now instead need to do 
```golang
log.SetDefault(log.NewLogger(log.NewTerminalHandlerWithLevel(os.Stderr, log.LevelInfo, true)))
```
See more about reasoning here: https://github.com/ethereum/go-ethereum/issues/28558#issuecomment-1820606613

go.mod

@@ -28,7 +28,6 @@ require (
 	github.com/fsnotify/fsnotify v1.6.0
 	github.com/gballet/go-libpcsclite v0.0.0-20190607065134-2772fd86a8ff
 	github.com/gballet/go-verkle v0.1.1-0.20231031103413-a67434b50f46
-	github.com/go-stack/stack v1.8.1
 	github.com/gofrs/flock v0.8.1
 	github.com/golang-jwt/jwt/v4 v4.5.0
 	github.com/golang/protobuf v1.5.3
@@ -64,13 +63,13 @@ require (
 	github.com/tyler-smith/go-bip39 v1.1.0
 	github.com/urfave/cli/v2 v2.25.7
 	go.uber.org/automaxprocs v1.5.2
-	golang.org/x/crypto v0.14.0
-	golang.org/x/exp v0.0.0-20230905200255-921286631fa9
-	golang.org/x/sync v0.4.0
-	golang.org/x/sys v0.13.0
-	golang.org/x/text v0.13.0
+	golang.org/x/crypto v0.15.0
+	golang.org/x/exp v0.0.0-20231110203233-9a3e6036ecaa
+	golang.org/x/sync v0.5.0
+	golang.org/x/sys v0.14.0
+	golang.org/x/text v0.14.0
 	golang.org/x/time v0.3.0
-	golang.org/x/tools v0.13.0
+	golang.org/x/tools v0.15.0
 	gopkg.in/natefinch/lumberjack.v2 v2.0.0
 	gopkg.in/yaml.v3 v3.0.1
 )
@@ -136,8 +135,8 @@ require (
 	github.com/tklauser/go-sysconf v0.3.12 // indirect
 	github.com/tklauser/numcpus v0.6.1 // indirect
 	github.com/xrash/smetrics v0.0.0-20201216005158-039620a65673 // indirect
-	golang.org/x/mod v0.12.0 // indirect
-	golang.org/x/net v0.17.0 // indirect
+	golang.org/x/mod v0.14.0 // indirect
+	golang.org/x/net v0.18.0 // indirect
 	google.golang.org/protobuf v1.27.1 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	rsc.io/tmplfunc v0.0.3 // indirect