fix(cli) CA Cert option for CLI commands

[xiphl]

When running CLI commands against a remote instance of datahub, there may be SSL related errors when connecting to the GMS.
While there is an option for ingestion (specify in the recipe), there should be an option for the user to define the CA cert when interacting with the remote instance for the other commands. Basically this PR adds ca_cert for requests.session().

Checklist

• The PR conforms to DataHub's Contributing Guideline (particularly Commit Message Format)
• Links to related issues (if applicable)
• Tests for the changes have been added/updated (if applicable)
• Docs related to the changes have been added/updated (if applicable)

[github-actions]

Unit Test Results (build & test)

  45 files  ±0    45 suites  ±0   12m 24s ⏱️ + 1m 4s
505 tests ±0  449 ✔️ ±0  56 💤 ±0  0 ❌ ±0 

Results for commit 2b9548a. ± Comparison against base commit f2e2a4d.

[github-actions]

Unit Test Results (metadata ingestion)

       5 files  ±0         5 suites  ±0   38m 56s ⏱️ + 3m 28s
   276 tests ±0     266 ✔️ ±0    6 💤 ±0  2 ❌ ±0  2 🔥 ±0 
1 243 runs   - 4  1 203 ✔️  - 2  28 💤  - 6  6 ❌ +2  6 🔥 +2 

For more details on these failures and errors, see this check.

Results for commit 2b9548a. ± Comparison against base commit f2e2a4d.

[xiphl]

Erm, it seems as though the failure is related to #3961 ?

[shirshanka]

Thanks for the PR @xiphl. The configuration and code differences between cli_utils and rest_emitter is not something we want to continue encouraging. If you can hold off on us merging this PR, we will probably have a simplification to cli-utils coming soon where we will unify the underlying classes (and the resulting config) to communicate with DataHub. Let us know if that works for you.

[xiphl]

I agree that it makes more sense to have a single config for emitter and cli, so I look forward to the revised implementation.