Support custom test commands

I have checked that this feature is not already implemented

• This feature does not exist

Use case

The current LSP attempts to automatically determine the command to run tests using the Test Explorer, however this doesn't work for all scenarios. For example, Rails applications use bin/rails test out of the box.

The current commands generated by the LSP do not work for all codebases, so allowing developers to customize the test command would make the Test Explorer functionality more useful for all codebases.

Description

I would like to be able to customize the command used for the test explorer to run tests, for example bin/rails test

Implementation

In the Code Lens command creation, prefer to read from the extension configuration instead of the base command: https://github.com/Shopify/ruby-lsp/blob/main/lib/ruby_lsp/listeners/code_lens.rb#L210-L225

Start in lib/ruby_lsp/listeners/code_lens.rb at the Code Lens command creation around lines 210-225, then trace how extension configuration is read. Verify that a configured test command such as bin/rails test is preferred over the generated base command when the Test Explorer runs tests.