Chore: Make cgo optional (for sqlite) (#108756)

* make cgo optional for sqlite

* update go.mod; check error code differently

* reduce api surface even more

* move test errors into sqlite package

* add a comment

pkg/util/sqlite/sqlite_nocgo.go

@@ -0,0 +1,24 @@
+//go:build !cgo
+
+package sqlite
+
+import "modernc.org/sqlite"
+
+//
+// FIXME (@zserge)
+//
+// This non-CGo "implementation" is merely a stub to make Grafana compile without CGo.
+// Any attempts to actually use this driver are likely to fail at runtime in the most brutal ways.
+//
+
+type Driver = sqlite.Driver
+
+func IsBusyOrLocked(err error) bool {
+	return false // FIXME
+}
+func IsUniqueConstraintViolation(err error) bool {
+	return false // FIXME
+}
+func ErrorMessage(err error) string {
+	return "" // FIXME
+}