system: handle SIGTERM signals

[mrfelton]

This pull request introduces signal handling to gracefully shut down the application upon receiving SIGTERM or SIGINT signals, and updates dependencies accordingly.

Dependency Updates:

• Cargo.toml: Added the signal feature to the tokio dependency. ([Cargo.tomlL27-R27](https://github.com/lndk-org/lndk/pull/151/files#diff-2e9d962a08321605940b5a657135052fbcef87b5e360662bb527c96d9a615542L27-R27))

Signal Handling Implementation:

• src/main.rs:
  • Imported signal and SignalKind from tokio::signal::unix. ([src/main.rsL26-R29](https://github.com/lndk-org/lndk/pull/151/files#diff-42cb6807ad74b3e201c5a7ca98b911c5fa08380e942be6e4ac5807f8377f87fcL26-R29))
  • Set up signal handlers for SIGTERM and SIGINT in the main function. ([src/main.rsR123-R126](https://github.com/lndk-org/lndk/pull/151/files#diff-42cb6807ad74b3e201c5a7ca98b911c5fa08380e942be6e4ac5807f8377f87fcR123-R126))
  • Added branches to the select! macro to handle SIGTERM and SIGINT signals, logging a shutdown message for each. ([src/main.rsR137-R142](https://github.com/lndk-org/lndk/pull/151/files#diff-42cb6807ad74b3e201c5a7ca98b911c5fa08380e942be6e4ac5807f8377f87fcR137-R142))

Fixes #150

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 10 lines in your changes missing coverage. Please review.

Project coverage is 0.00%. Comparing base (259de8b) to head (ef878ee).
Report is 5 commits behind head on master.

Files with missing lines	Patch %	Lines
src/main.rs	0.00%	10 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff           @@
##           master    #151   +/-   ##
======================================
  Coverage    0.00%   0.00%           
======================================
  Files           1       1           
  Lines         105     115   +10     
======================================
- Misses        105     115   +10     

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[orbitalturtle]

Closing since #152 is now merged