CDRIVER-4062 test load balancer on evg (#837)

Add tasks to the Evergreen configuration based to test against a loadbalanced cluster.
- Tests with auth+SSL and with no auth+SSL on both server version 5.0 and latest.
- Runs tests against: new load balanced tests, all unified tests, retryable reads, retryable writes, change streams, and the C driver specific /loadbalanced/* tests.

Update test-libmongoc to support testing against a load balancer.
- Support the environment variable MONGOC_TEST_LOADBALANCED to enable testing against load balancers in test-libmongoc.
Support the environment variables SINGLE_MONGOS_LB_URI, MULTI_MONGOS_LB_URI to set URIs for test clients.
- Mock the serviceId when MONGOC_TEST_LOADBALANCED is true.
- Support multiple occurrences of the -l flag in test-libmongoc and alias the flag as --match.
- Remove unnecessary constraint of retryable writes tests for replica sets.

CDRIVER-4060 add remaining support to the unified test runner for the new loadbalancer spec tests.
- Iterate the first result of a FindCursor in the createFindCursor operation.
- Support appname as a URI parameter.
- Skip listening or comparing CMAP (Connection Monitoring and Pooling) events, since the C driver does not implement CMAP.