feat(dashboard): embedded assets into binary for release builds

[BugenZhao]

I hereby agree to the terms of the RisingWave Labs, Inc. Contributor License Agreement.

What's changed and what's your intention?

See #15280 (comment) for the background.

Introduce a dashboard crate for building and embedding assets. The embedded mode and proxied mode will be chosen based on configuration.

risingwave/src/meta/dashboard/src/lib.rs

Lines 22 to 36 in 1dab410

	/// The router for the dashboard.
	///
	/// Based on the configuration, it will either serve the assets embedded in the binary,
	/// or proxy all requests to the latest static files built and hosted on GitHub.
	///
	/// - For development and CI builds, the requests to the dashboard will be proxied. This
	/// is to reduce the build time and eliminate the dependency on `node`, so that the
	/// developer experience can be better.
	///
	/// - For release builds, the assets will built in the build script and embedded in the
	/// binary. This is to make the deployment easier and the dashboard more reliable
	/// without relying on external or remote resources.
	///
	/// If you're going to develop with the dashboard, see `dashboard/README.md` for more
	/// details.

Note that there's no actual change on the binary release or docker release. This PR is mainly focusing on introducing the functionality. Will deprecate the old external ui approach in next PRs.

Checklist

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
• All checks passed in ./risedev check (or alias, ./risedev c)

Documentation

• My PR needs documentation updates. (Please use the Release note section below to summarize the impact on users)

Release note

If this PR includes changes that directly affect users or other significant modifications relevant to the community, kindly draft a release note to provide a concise summary of these changes. Please prioritize highlighting the impact these changes will have on users.

[BugenZhao]

• feat: use embedded dashboard in docker release #15687
• feat(dashboard): embedded assets into binary for release builds #15656 👈
• refactor(risedev): deprecate steps for building dashboard #15655
• main

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[xxchan]

Generally LGTM

[xxchan]

What's the size of the embedded asset?

[BugenZhao]

Currently 3.5 MB. We can also enable compression for embedded files if they're getting larger.

❯ du -sh dashboard/out                                                                                                                
3.5M    dashboard/out

[xxchan]