Create Uninstaller for each platform

[stephenhensley]

For windows:

strip entry from PATH variable for the bin/ directory.

For macOS:

run brew uninstall on the necessary tools

strip entry from PATH for arm toolchain.

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My concerns about this (mostly on Mac) is that the user may have openocd/dfu-util, etc. installed for other reasons. In which case this would still uninstall them. Since this is a system-wide installation, not just something like the Windows version that is self contained.

That said, we can just mention that.