DRIVERS-555 Add spec/prose tests for client-side operations timeout

[divjotarora]

Right now, all of the new tests are in the client-side-operations-timeout directory. When we convert the spec from Google Docs to RST, however, we'll make the required changes to the existing specs and move tests to other directories as needed.

Salient points for reviewers:

• The generate-basic-tests.py and all .yml.template files are used for test generation. Each .yml.template file defines a set of tests to run and the corresponding generated .yml file contains each of those tests for each operation. It might be easier to review the template files and just skim over the generated ones.
• I've added a schema-1.2.json to reflect the changes to the unified test format. All YAML files that use these new features should declare a schemaVersion of 1.2. Note that 1.1 was skipped because it's being taken by the versioned API project, which will almost definitely close out before this one.

TODO:

• Figure out if the generate-basic-tests.py script needs to account for the createIndexes operation. The current version only tests createIndex.
• Modify Travis to fail if the YAML templates are out of sync with the generated files.
• Add new required features to the unified test format spec.
• Add a new JSON schema to reflect the unified test format changes.

Once we know where these tests are actually ending up, we should also update the Makefile to run JSON schema checks against the test files.

[durran]

TXN looks good.

[iwysiu]

transactions look good

[divjotarora]

I'm going to close out this PR because it's gotten very large. I will rebase everything on the main branch, update the schema version for the unified test format spec, and make a new PR in draft mode with the final changes.