Bazel toolchain rewrite

[Ford544]

This updates the bazel toolchain and migrates the package manager (adapting the changes from #2206 ):

• Migrate to aspect_rules
• Migrate to pnpm from yarn

Package Comparison (main vs bazel-aspect-rules)

Element	@dataform/core	@dataform/cli
package.json	Only resolutions (inherited from root package.json) changed for pnpm: stripped **/ and @google-cloud/storage/**/ glob prefixes from keys, and bumped protobufjs resolution from ^7.0.0 to ^7.6.5. All other fields are identical.	Same resolutions diff as @dataform/core. All other fields (including dependencies) are identical.
Entry points	No difference ("main": "bundle.js" in package.json; bundler entry point index.ts and identical exported keys).	No difference ("main": "bundle.js" and "bin": {"dataform": "bundle.js"} in package.json; bundler entry points index.ts and worker.ts).
bundle.js format	No difference (Webpack libraryTarget: "commonjs-module" CommonJS bundle from CommonJS ts_library output).	No difference (Rollup bundles ESM ts_library output esm/index.js into a CommonJS bundle.js with format = "cjs" in pkg_bundle, same as main).
.d.ts files	Semantically identical (bundle.d.ts has 13 top-level type aliases emitted as type instead of declare type and minor tuple indentation formatting; all types and exports are identical).	No difference (no .d.ts files in package).

Compilation validation:

Compiled a sample Dataform project containing sqlx and js actions, a yaml action spec and a js include using the published version 3.0.71 and the current build - resulting json verified to be identical.

[apilaskowski]

Please convert this to PR when it is ready for review.