Improve log message and error when database cannot be deleted due to pending connections

Per discussion for CBSE-10684 :

1. Provide an optional enum indicating the usage (e.g. query, replicator, application) when opening the c4Database.

2. Improve logging messages about pending database connections when deleting the database (data file) by providing the usage information. 

3. Throw errors to fail faster (maybe after waiting for a minimum timeout?) when cannot deleting the database (data file) due to some pending database connections. If waiting for the connections for application alone, the error code could be different.

4. Synchronize timeout between waiting for the pending connections to close and the timeout waiting for web socket to close. CBL-2383