[experiment] add alternative wasm sqlite3 implementation available via build-tag (#2863)

This allows for building GoToSocial with [SQLite transpiled to WASM](https://github.com/ncruces/go-sqlite3) and accessed through [Wazero](https://wazero.io/).

vendor/github.com/ncruces/go-sqlite3/internal/util/pointer.go

@@ -0,0 +1,11 @@
+package util
+
+type Pointer[T any] struct{ Value T }
+
+func (p Pointer[T]) unwrap() any { return p.Value }
+
+type PointerUnwrap interface{ unwrap() any }
+
+func UnwrapPointer(p PointerUnwrap) any {
+	return p.unwrap()
+}