mongo: connector validations

[jgao54]

• Make sure necessary collections and changestream permissions are granted during validation.
• Check what happens if user use a readConcern that's not 'majority' via URI -- and handle validation accordingly.

[jgao54]

We now have connection validation for:

• mongo version >= 5.1.0
• mongo cluster is 'replicaSet'
• storage engine == 'wiredTiger'
• oplog retention hours > 24
• connection string is valid
• separate username/password fields (not part of connection string)

We also will ignore the following and use our default for:

• compression
• read concern (majority)

#3166
#3168
#3181 (frontend)

[IvanTakarlikov-st]

@jgao54 Hey! Can you please explain why do you expect to have mongo version > 5.1?
Is there any features which are not available in Mongo 4.4?

[IvanTakarlikov-st]

I've created PR to downgrade required mongo version, so far don't see any issues with lower version of mongo.
#3453
Please let me know if you know any.