Refactor Router Logger (#17308)

Make router logger more friendly, show the related function name/file/line.

[BREAKING]
This PR substantially changes the logging format of the router logger. If you use this logging for monitoring e.g. fail2ban you will need to update this to match the new format.

modules/web/routing/funcinfo_test.go

@@ -0,0 +1,81 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package routing
+
+import (
+	"fmt"
+	"testing"
+)
+
+func Test_shortenFilename(t *testing.T) {
+	tests := []struct {
+		filename string
+		fallback string
+		expected string
+	}{
+		{
+			"code.gitea.io/routers/common/logger_context.go",
+			"NO_FALLBACK",
+			"common/logger_context.go",
+		},
+		{
+			"common/logger_context.go",
+			"NO_FALLBACK",
+			"common/logger_context.go",
+		},
+		{
+			"logger_context.go",
+			"NO_FALLBACK",
+			"logger_context.go",
+		},
+		{
+			"",
+			"USE_FALLBACK",
+			"USE_FALLBACK",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(fmt.Sprintf("shortenFilename('%s')", tt.filename), func(t *testing.T) {
+			if gotShort := shortenFilename(tt.filename, tt.fallback); gotShort != tt.expected {
+				t.Errorf("shortenFilename('%s'), expect '%s', but get '%s'", tt.filename, tt.expected, gotShort)
+			}
+		})
+	}
+}
+
+func Test_trimAnonymousFunctionSuffix(t *testing.T) {
+	tests := []struct {
+		name string
+		want string
+	}{
+		{
+			"notAnonymous",
+			"notAnonymous",
+		},
+		{
+			"anonymous.func1",
+			"anonymous",
+		},
+		{
+			"notAnonymous.funca",
+			"notAnonymous.funca",
+		},
+		{
+			"anonymous.func100",
+			"anonymous",
+		},
+		{
+			"anonymous.func100.func6",
+			"anonymous.func100",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := trimAnonymousFunctionSuffix(tt.name); got != tt.want {
+				t.Errorf("trimAnonymousFunctionSuffix() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}