wit: Migrate from `float32`/`float64` to `f32`/`f64`

Per the discussion in https://github.com/WebAssembly/component-model/issues/277, there seems to be consensus for migrating the names of the types `float32` and `float64` to `f32` and `f64`.

A plan for `f32`/`f64` is:
- [x] Make wit-parser accept `f32` and `f64` as aliases for `float32` and `float64`. https://github.com/bytecodealliance/wasm-tools/pull/1356
- [x] Wait until that's in a release and the major tools have updated.
- [ ] Update Wit files, documentation, pretty-printers, etc. to `f32`/`f64`.
- [ ] After some time, add a deprecation warning for `float32`/`float64` pointing users to `f32`/`f64`
- [ ] After some time, remove `float32`/`float64`