feat: Added CI and Release Builds for Debian, Windows and Mac

[GooseLF]

• Added the following builds:

  • build-executable-debian.yml
  • build-executable-windows.yml
  • build-executable-macosx.yml
  • sql-deployment-tools-ci.yml
    • Contains pre-commit.

• Moved sql folder and python files into /src.

• Created platform directory containing build scripts for different operating systems.

• Added pre-commit and associated configuration. (Runs in CI Build).

Closes #4.

Even squashed the commits for you 😉

[GooseLF]

Made changes as per PR review by @gvee-uk.

• Removed dependency on testresources as no longer needed.
• Moved pre-commit into it's own requirements file, test.txt
• Changed references to "unix" in `platform/linux_debian/build.sh"
• Changed references to "unix" in `platform/mac_osx/build.sh"
• Added a \ on line 106 of README.md so that MarkdownLint is happy with the line length but the command will still work if copy/pasted.
• Added stage for commitizen in .pre-commit-config.yaml
• Squashed commits

[GooseLF]

• Added .markdownlint.yaml
• Edited command on line 106 of README.md to be one line
• Included requirements/base.txt in requirements/test.txt
• Squashed commits (again)