[BOLT] New profile format

Summary:
A new profile that is more resilient to minor binary modifications.

BranchData is eliminated. For calls, the data is converted into instruction
annotations if the profile matches a function. If a profile cannot be matched,
AllCallSites data should have call sites profiles.

The new profile format is YAML, which is quite verbose. It still takes
less space than the older format because we avoid function name repetition.

The plan is to get rid of the old profile format eventually.

merge-fdata does not work with the new format yet.

(cherry picked from FBD6753747)