Add `getbpm` and `setbpm` to boot functions #206

Job	Run time
cancel-previous-runs	3s
nix-build (tidal, ubuntu-latest)	3m 34s
nix-fmt-check	17s
nix-build (tidal, macos-latest)	6m 22s
nix-build (tidal-link, ubuntu-latest)	1m 39s
nix-build (tidal-link, macos-latest)	3m 26s
nix-build (tidal-parse, ubuntu-latest)	4m 29s
nix-build (tidal-parse, macos-latest)	7m 43s
	27m 33s

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