feat(Gate): Consistency Check with the Pool

[nicoprow]

Description

This pull request introduces a consistency check to the Gate which checks whether referenced BPNs in the output stage are still existing in the Pool. If a discrepancy has been found it will be written as an error in the sharing state for the business partner record in question.

For testing I recommend the following:

1. setup the full golden record process
2. Share some business partners linking to different golden records
3. Set the concistency check to a fairly regular interval in the Gate's configureation
4. See in the logs whether the consistency checks works without issues
5. Go to the Pool database and rename some linked BPNs
6. After the next consistency check is done check the sharing states of affected business partner records
7. You should see the errors in the sharing states

I did not add any automatic integration as the setup of these tests via mocking is very time consuming. We should decide whether we want to invest the time into actually creating such tests or keep those as manual tests.

Implements #1130

Pre-review checks

Please ensure to do as many of the following checks as possible, before asking for committer review:

• DEPENDENCIES are up-to-date. Dash license tool. Committers can open IP issues for restricted libs.
• Copyright and license header are present on all affected files

[SujitMBRDI]

Changes LGTM 🚀
The tests I have performed -

1. Reduced scheduling time for consistency to 10seconds
2. Created golden record through round trip
3. Changed BPN number from POOL database
4. And checked scheduling - which worked as expected
5. Also got sharing state error with error code - BpnNotInPool

Regarding automated test, yes I agree that this will be time consuming thing and we'll achieve sometime later.