Auto merge of #21376 - JoshBrudnak:master, r=jdm
Auto merge of #21376 - JoshBrudnak:master, r=jdm

Add rustfmt command to devenv commands

Added the rustfmt command to devenv commands which runs cargo fmt on a specified directory.

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #21374

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- [ ] There are tests for these changes OR
- [X] These changes do not require tests because they only included a simple command that was added to the devenv_commands python script.

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