Upcoming updates and a new name for rules_swiftformat

[cgrindel]

I have finally had the opportunity to circle back to rules_swiftformat and make some long-overdue updates. Here is a quick overview of the recent and upcoming changes:

• By default, this framework will download pre-built executables from nicklockwood/SwiftFormat.
• Support other Swift code hygiene utilities like apple/swift-format and realm/SwiftLint.
• Demonstrate how to use rules_swift_package_manager to build the utilities.
• Remove the dependency on the now deprecated rules_spm framework.
• Support bzlmod.

Once bzlmod support is ready, I will submit it for inclusion in the Bazel Central Repository. Since the functionality in this repository is expanding beyond supporting SwiftFormat, I want to be sure that the repository/module name fits. Right now, the best name I have come up with is rules_swift_tidy. However, I am open to other ideas. So, if you have any suggestions, please let me know in the comments.