cluster: add application_info

[dkropachev]

Implement clustr.application_info to make driver send following startup options to server:

1. APPLICATION_NAME - ID what application is using driver, example: repo of the application
2. APPLICATION_VERSION - Version of the application, example: release version or commit id of the application
3. CLIENT_ID - unique id of the client instance, example: pod name

All strings.

Fix: #485

Results:

cqlsh> SELECT * FROM system_views.clients;

 address    | port  | client_options                                                                                                                                                                             | connection_stage | driver_name            | driver_version | hostname   | keyspace_name | protocol_version | request_count | ssl_cipher_suite | ssl_enabled | ssl_protocol | username
------------+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------+------------------------+----------------+------------+---------------+------------------+---------------+------------------+-------------+--------------+-----------
 172.17.0.1 | 55756 | {'APPLICATION_NAME': 'app_name', 'APPLICATION_VERSION': '1.1.1', 'CLIENT_ID': 'my_client_id', 'CQL_VERSION': '3.4.7', 'DRIVER_NAME': 'ScyllaDB Python Driver', 'DRIVER_VERSION': '3.29.3'} |            ready | ScyllaDB Python Driver |         3.29.3 | 172.17.0.1 |          null |                5 |            16 |             null |       False |         null | anonymous
 172.17.0.1 | 55762 | {'APPLICATION_NAME': 'app_name', 'APPLICATION_VERSION': '1.1.1', 'CLIENT_ID': 'my_client_id', 'CQL_VERSION': '3.4.7', 'DRIVER_NAME': 'ScyllaDB Python Driver', 'DRIVER_VERSION': '3.29.3'} |            ready | ScyllaDB Python Driver |         3.29.3 | 172.17.0.1 |          null |                5 |             1 |             null |       False |         null | anonymous

(4 rows)

Pre-review checklist

• I have split my patch into logically separate commits.
• All commit messages clearly explain what they change and why.
• I added relevant tests for new features and bug fixes.
• All commits compile, pass static checks and pass test.
• PR description sums up the changes and reasons why they should be introduced.
• I have provided docstrings for the public items that I want to introduce.
• I have adjusted the documentation in ./docs/source/.
• I added appropriate Fixes: annotations to PR description.

[Lorak-mmk]

Please also add an integration test running on C* that uses the new API and verifies the data in client_info.