New API call to perform compaction

[idanovo]

We need to have a new API call that "compacts" all the sealed tokens + staging token for a given branch.
The process is detailed in the compactor design

[idanovo]

Graveler function	Tested	Controller function	Tested	AI
ResetKey	X	ResetBranch	V	Add a controller test for ResetKey for a compacted branch when we add the CompactBranch API call
ResetPrefix	X	ResetBranch	V	Add a controller test for ResetPrefix for a compacted branch when we add the CompactBranch API call
prepareForCommitIDUpdate	X	Revert (dirty branch)	V	Added a test in graveler testsShould also add a test in the controller once we have the CompactBranch API call
prepareForCommitIDUpdate	X	CherryPick (dirty branch)	V	Add a controller test for CherryPick for a compacted branch when we add the CompactBranch API call
prepareForCommitIDUpdate	X	UpdateBranch (dirty branch)	X	Add a controller test for ResetPrefix for a compacted branch when we add the CompactBranch API call
prepareForCommitIDUpdate	X	Merge (dirty branch)	V	Added a test in graveler testsShould also add a test in the controller once we have the CompactBranch API call
prepareForCommitIDUpdate	X	Import (dirty branch)	X	Add a controller test for ResetPrefix for a compacted branch when we add the CompactBranch API call