feat: add --prune option to remove orphaned functions after deploy

[IdrisCelik]

See #3719

[coveralls]

Pull Request Test Coverage Report for Build 15882596182

Details

• 49 of 61 (80.33%) changed or added relevant lines in 5 files are covered.
• 5 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.07%) to 55.553%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
cmd/root.go	0	1	0.0%
cmd/functions.go	0	2	0.0%
internal/functions/deploy/deploy.go	34	43	79.07%

Files with Coverage Reduction	New Missed Lines	%
internal/gen/keys/keys.go	5	12.9%

Totals
Change from base Build 15872705219:	0.07%
Covered Lines:	6063
Relevant Lines:	10914

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💛 - Coveralls

[IdrisCelik]

Awesome, thanks for completing!