SW-426: fixes for the new tests in t_radb.py. Main changes: a claim cannot have zero duration anymore. a task which goes to conflict releases its claimed claims

Tas #11049: Add description to getResourceGroupMemberships and add resource type to the resulting dict.

Task #9893: Restore API of get_resource_claimable_capacity (which matches the tests and the calls in ResourceAssigner). There is no apparent reason the input parameters need to be returned as an output dict.

Task #9893: fixed bug in deleteResourceClaims() where resource_claim_ids could be empty, resulting in a failing DB-query

Task #10902: fixed and improve (on speed) the rebuild_resource_usages_table_from_claims nethod. Extended the test_resource_usages. Added performance test script which proves the new rebuild is O(N) and about n order of magnitude faster than before.

Task #10902: refactored many selects on resource_usage into method get_resource_usage_at_or_before. Added logging when we detect that a usage_at_start is not found, then the usages table is rebuild for that resource, and then we search again for usage_at_start. Only if not found again, raise exception. This fixes the test for the bug found on production. Still to do: performance increase for rebuild usage table.

Task #10902: added test_reinsert_task test method to prove a bug in production. unfortunately the bug is not proven... so, let's keep this test as reference, and think of a better solution.

Task #10660: 1) logging of db notices also when db raises exception. 2) return dict instead of int for get_resource_claimable_capacity

Task #10813: Improved reconnect to RADB mechanism in _executeQuery() such that self.cursor.execute(query, qargs) is always called from within a try-statement

Task #10811: radb.py: use db table resource_monitoring.resource_usage for method getResourceUsages. adapted code using getResourceUsages.

Task #10811: added argument where_task_ids to updateResourceClaims method, so we can update all claims for one or more task(s) in one call

Task #10811: added option to get claimable_capacity in method getResources. fixed get_max_resource_usage_between. added little bit of test code to setup some test tasks and claims for demo

Task #10811: intermediate commit for method get_conflicting_overlapping_claims. Needs to be fixed, but you get the idea.

Task #10811: made functions (and tests for) get_conflicting_overlapping_tasks and get_conflicting_overlapping_claims