[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/alloc_slice.go

@@ -0,0 +1,25 @@
+//go:build !(darwin || linux) || !(amd64 || arm64 || riscv64) || sqlite3_noshm || sqlite3_nosys
+
+package util
+
+import "github.com/tetratelabs/wazero/experimental"
+
+func sliceAlloc(cap, max uint64) experimental.LinearMemory {
+	return &sliceBuffer{make([]byte, cap), max}
+}
+
+type sliceBuffer struct {
+	buf []byte
+	max uint64
+}
+
+func (b *sliceBuffer) Free() {}
+
+func (b *sliceBuffer) Reallocate(size uint64) []byte {
+	if cap := uint64(cap(b.buf)); size > cap {
+		b.buf = append(b.buf[:cap], make([]byte, size-cap)...)
+	} else {
+		b.buf = b.buf[:size]
+	}
+	return b.buf
+}