Git diff improvements

[GrantBirki]

Updates to examples:

• README.md: Upgraded the version of actions/checkout used in the examples from v3 to v4. [1] [2]

Addition of new input options:

• README.md: Added git_options and git_diff_file to the list of input options.
• action.yml: Added git_options and git_diff_file as new input options for the action.

Modifications to the gitDiff function and its related tests:

• __tests__/main.test.js: Updated the tests for the gitDiff function to reflect the changes in its implementation.

• src/functions/git-diff.js: Modified the gitDiff function to support the new git_options and git_diff_file input options. The function can now read the diff from a file and pass additional options to the git binary. [1] [2] [3] [4]

• src/main.js: Updated the run function to await the gitDiff function.Changes to the gitDiff function:

• src/functions/git-diff.js: The gitDiff function is now an asynchronous function that uses promisify from the util module to convert exec to a promise-based function. This change allows us to use await to wait for the execAsync function to complete before proceeding.

• src/functions/git-diff.js: The gitDiff function now accepts git_options as an input, which are passed to the git diff command. This change allows users to specify additional options for the git binary. [1] [2]

• src/functions/git-diff.js: Additional logging has been added to the gitDiff function to provide information about the total number of files changed in the raw diff and the JSON diff. [1] [2]

Addition of git_options input parameter:

• README.md: Added documentation for the new git_options input parameter.
• __tests__/main.test.js: Added a new environment variable for git_options in the beforeEach function.
• action.yml: Added a new git_options input parameter with a default value of "--no-color --full-index".

Other changes:

• src/main.js: The run function now awaits the gitDiff function to ensure it completes before proceeding.