Support visionOS and watchOS

## Goal

Make this project work for all Swift platforms.

## Work plan

- [ ] Clone https://github.com/Alamofire/Alamofire
- [ ] Run the configure script. That is our basis to begin
- [ ] Get all tests to run locally across the whole matrix and document this
- [ ] Rip out CocoaPods and every other part we don't need
- [ ] Get all tests to run locally across the whole matrix and document this
- [ ] Rip out the Swift package feature except for the features we have in this project
- [ ] Get all tests to run locally across the whole matrix and document this
- [ ] Show diff of that working copy versus what is here
- [ ] Make decisions about any differences in our/their best practices, cite them, change to our best practices
- [ ] Get all tests to run locally across the whole matrix and document this
- [ ] Show diff of that working copy versus what is here
- [ ] Stash your work
- [ ] Somehow back our way into producing that working copy by updating our recipe
- [ ] Diff your working copy and update recipe until there the recipe materially produces that working copy
- [ ] Get all tests to run locally across the whole matrix and document this
- [ ] Publish the new recipe!
- [ ] Repeat this process every year

Start with the configure script and the existing test setup, then compare the project recipe with the Alamofire working copy named in the plan. Determine what is needed for visionOS and watchOS, verify the full platform test matrix, document the results, and publish an updated recipe.

Written by the indexing model from the issue text.