refactor(logging): add a logging abstraction and move the job logger onto it (#1295)

Add `act/common/logging`: a printf-style `Logger` on a slog-shaped `Handler`, with a logrus-backed handler as the only backend, plus a `logtest` handler for tests. Move the job logger onto it: `common.Logger` returns `*logging.Logger`, the job log formatters and the `Reporter` hook become handlers, and composite step IDs travel in the context.

Logging is tightly coupled to logrus types (hooks, formatters, `Entry.Data`). Going through our own interface first lets the remaining call sites move over with unchanged behavior, and lets the backend be swapped for `log/slog` in one place afterwards. The global process logger and its masking formatter stay on logrus for now.

Assisted-by: Codet
Co-authored-by: bircni <[email protected]>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1295
Reviewed-by: bircni <[email protected]>

internal/app/run/logging.go

@@ -4,21 +4,15 @@
 package run
 
 import (
-	"io"
-
-	log "github.com/sirupsen/logrus"
+	"gitea.com/gitea/runner/act/common/logging"
 )
 
 // NullLogger is used to create a new JobLogger to discard logs. This
 // will prevent these logs from being logged to the stdout, but
-// forward them to the Reporter via its hook.
+// forward them to the Reporter via its handler.
 type NullLogger struct{}
 
-// WithJobLogger creates a new logrus.Logger that will discard all logs.
-func (n NullLogger) WithJobLogger() *log.Logger {
-	logger := log.New()
-	logger.SetOutput(io.Discard)
-	logger.SetLevel(log.TraceLevel)
-
-	return logger
+// WithJobLogger returns a handler that discards all logs.
+func (n NullLogger) WithJobLogger() logging.Handler {
+	return logging.DiscardHandler
 }