[FEAT] add spark-connect protocol

[andrewgazelka]

This PR adds a script-based approach for generating the Spark Connect protobuf code, eliminating the need for developers to have the protobuf compiler (protoc) installed locally.

Key changes:

• Added a new spark-connect-script crate that uses tonic-build to compile the .proto files into Rust code at build time
• The script outputs the generated code as a string which can then be stored directly in the codebase
• Added the generated Rust code to src/spark-connect/src/lib.rs
• Updated workspace members to include both new crates
• The proto files are copied from Spark's codebase and cover the full Connect protocol including base, catalog, commands, common, expressions, relations and types

This approach makes it easier for developers to work with the Spark Connect protocol since they don't need to manage protoc installation and versioning. The generated code is checked into the repo and can be reviewed/updated as needed.

Dependencies added:

• prost: For protobuf encoding/decoding
• prost-types: Common protobuf type definitions
• tonic: For gRPC functionality

[codspeed-hq]

CodSpeed Performance Report

Merging #3189 will not alter performance

_{Comparing andrew/spark-connect (ab6c56b) with main (baca61e)}

Summary

✅ 17 untouched benchmarks

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.90%. Comparing base (d8cdf36) to head (15ed80d).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3189      +/-   ##
==========================================
- Coverage   78.60%   77.90%   -0.71%     
==========================================
  Files         637      638       +1     
  Lines       78225    79207     +982     
==========================================
+ Hits        61491    61707     +216     
- Misses      16734    17500     +766     

Files with missing lines	Coverage Δ
src/spark-connect/src/lib.rs	0.00% <ø> (ø)

... and 19 files with indirect coverage changes

[samster25]

let place this crate under filepaths:

src/scripts/spark-connect-generation

[andrewgazelka]

ab6c56b

[samster25]

LGTM