Update rubocop to support ruby 3.2

[kartiki975]

This pull request includes updates to the .rubocop.yml configuration, upgrades the rubocop gem in the Gemfile, and applies various code improvements across multiple controllers in the Shipit API. The changes focus on improving code readability, modernizing syntax, and disabling select RuboCop rules. Some rules were disabled to find the fastest way to do the Rails 8.0 upgrade.

RuboCop Configuration and Gem Updates:

• Removed the inherit_gem directive for rubocop-shopify and added exclusions for Layout/LineLength in .rubocop.yml.
• Disabled several RuboCop rules (e.g., Metrics/ClassLength, Style/Documentation, Metrics/AbcSize) in .rubocop.yml.
• Upgraded the rubocop gem from version 1.18.3 to ~> 1.48.0 in the Gemfile.

Syntax Modernization:

• Replaced hash rockets with Ruby 2.7+ shorthand syntax for keyword arguments in methods like render_resources and trigger_deploy. [1] [2]
• Simplified conditional assignments and method calls, e.g., commits.newer_than(stack.last_deployed_commit) is now inline.

Code Readability Improvements:

• Standardized array formatting for permissions (e.g., %i[index show] → %i[index show]). [1] [2]
• Improved method naming for clarity, such as renaming has_basic_credentials? to basic_credentials?.

Controller Enhancements:

• Refactored logic in StacksController to streamline repository filtering and parameter handling. [1] [2]
• Updated MergeRequestsController to handle edge cases more concisely, including merged pull requests and cancellations.

Note for reviewers

I will squash all the commits down before merging the PR.

[bostonou]

Approved, with another top-hat cycle expected

[kartiki975]

A final top-hat has been completed with smoke testing. Everything is behaving as expected.