add new functionality and improve backend server structure

- Enhance server functionality and optimize backend code
- Add multi-database support (PostgreSQL, MySQL, SQLite)

server/core_backend-server/tools/logger/log.go

@@ -0,0 +1,17 @@
+package logger
+
+import (
+	"log/slog"
+	"time"
+
+	"github.com/pocketbase/pocketbase/tools/types"
+)
+
+// Log is similar to [slog.Record] bit contains the log attributes as
+// preformatted JSON map.
+type Log struct {
+	Time    time.Time
+	Data    types.JSONMap[any]
+	Message string
+	Level   slog.Level
+}