feat: add concurrency limit for grpc server

[gaius-qi]

Description

This pull request introduces new rate limiting features for the download and upload gRPC servers in the dragonfly-client-config and makes associated updates to the dragonfly-client codebase. The most important changes include adding default rate limits, updating server structures to include these limits, and incorporating the ServiceBuilder to apply concurrency limits and load shedding.

Rate Limiting Features:

• dragonfly-client-config/src/dfdaemon.rs: Added functions default_download_request_rate_limit and default_upload_request_rate_limit to define default rate limits for download and upload requests. Updated DownloadServer and UploadServer structs to include request_rate_limit fields with default values. [1] [2] [3] [4] [5]

Dependency Updates:

• dragonfly-client/Cargo.toml: Updated the tower dependency to include additional features: limit, load-shed, and buffer.

Codebase Updates:

• dragonfly-client/src/grpc/dfdaemon_download.rs: Modified DfdaemonDownloadServer to include the config field, and used ServiceBuilder to apply concurrency limits and load shedding in the gRPC server setup. [1] [2] [3] [4] [5]
• dragonfly-client/src/grpc/dfdaemon_upload.rs: Incorporated ServiceBuilder to apply concurrency limits and load shedding in the gRPC server setup for the upload server. [1] [2] [3]

Related Issue

dragonflyoss/dragonfly#3811

Motivation and Context

Screenshots (if appropriate)

[codecov]

Codecov Report

Attention: Patch coverage is 88.88889% with 1 line in your changes missing coverage. Please review.

Project coverage is 33.12%. Comparing base (991ecd3) to head (2559da1).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
dragonfly-client/src/bin/dfdaemon/main.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #982      +/-   ##
==========================================
+ Coverage   33.07%   33.12%   +0.05%     
==========================================
  Files          59       59              
  Lines        9741     9750       +9     
==========================================
+ Hits         3222     3230       +8     
- Misses       6519     6520       +1     

Files with missing lines	Coverage Δ
dragonfly-client-config/src/dfdaemon.rs	49.89% <100.00%> (+0.81%)	⬆️
dragonfly-client/src/grpc/dfdaemon_download.rs	0.00% <ø> (ø)
dragonfly-client/src/grpc/dfdaemon_upload.rs	0.00% <ø> (ø)
dragonfly-client/src/bin/dfdaemon/main.rs	0.00% <0.00%> (ø)