WRP-2989 termserver action performance details logging

This PR adds the following features/enhancements to the request API:

Measure multiple metrics during execution of a request
Externally measured values, so they will be reported together with the internal ones
Valid JSON serialization of request hierarchies
Enable metrics by default in the default h2/mysql configurations

The execution times of the following commits parts are currently measured and reported:

preCommit - actual change request before commit, which makes changes in the CDO model based on the request parameters
idGeneration - New ID generation requests
commit - the execution time of the CDO commit
indexing - the execution time of the indexing of new/changed/deleted SNOMED CT components
traceability - execution time of the traceability service
preRequest - execution time of any pre commit request related task (IHTSDO bulk and single update endpoints)

IHTSDO / snow-owl