Issue status synchronization should be a standalone `sonar-migration-tool` command

[okorach-sonar]

Since issue status sync may be done:

• During the migrate command when the skip_project_data_migration is false (default)

• After a migration if skip_project_data_migration is true. In that case the migration only migrates projects configuration and a SQC scan has to be done to populate project data, after which issue status sync can be performed

• sonar-migration-tool should offer a standalone sync-issues command

• This command should sync all the issues of projects from a source SQS platform to the corresponding projects in SQC

• The mapping of project keys should be based on the SQC project key renaming conventions defined in the migration configuration (currently hardcoded as <org>_<projectKey> but will be configurable in the medium term based on issue The project key renaming strategy should be configurable #138

• Since the code may be slightly different on SQS and SQC the issue matching algorithm should not assume strict line number correspondance. A looser matching function is implemented at:

https://github.com/okorach/sonar-tools/blob/593226eb1492c54d1bfa282eb7ed4ba5bb44cea3/sonar/findings.py#L488
https://github.com/okorach/sonar-tools/blob/593226eb1492c54d1bfa282eb7ed4ba5bb44cea3/sonar/findings.py#L421
https://github.com/okorach/sonar-tools/blob/593226eb1492c54d1bfa282eb7ed4ba5bb44cea3/sonar/findings.py#L447

Basically the matching algorithm verifies an exact match based on several issue attributes.

• If an exact match is found, there's a match , and the sync is performed
• If no exact match is found, the matching algorithm compute an approximate match score, based on the correspondance of a certain number of issue attributes.
  • If a single approximate match is found, then this is the match, and the sync is performed
  • If multiple approximate matches are found, then there is no best match and in that case the sync of the source issue is skipped
  • If no approximate match is found, then there is no match and in that case the sync of the source issue is skipped