Store WASM UDF in meta store

[fuyufjh]

You can embed WASM binaries into SQL using base64 encoding. RW will upload the binary into object store with the path defined in the parameter wasm_storage_url.

Why not just storing them in meta store? In most cases the WASM won't be very big and meta store (will be migrated to RDBMS e.g. PostgresQL) should be good enough. I prefer to make it simple and avoid introduce new dependent systems.

A related discussion: #12982. Also recommend meta store for it in my opinion.

The wasm binary in e2e test is about 1.5MB after strip, 400KB after compression. It sounds okay to store them into meta.

Let me note it down as an issue as a reminder.

Originally posted by @fuyufjh in #14271 (comment)