Add Helm Chart variables to mount the Custom Azure Environment File

[chrisamert]

To get the Azure KeyVault Provider working in air-gapped or on-prem Azure clouds, the Custom Azure Environment file needs to be mounted on the KeyVault Provider pods. This change adds new variables to the Helm chart that allows this Volume Mount to be created.

Fixes #444

Reason for Change:

Enables the Helm Chart to configure a volume mount necessary for running the Azure KeyVault Provider in air-gapped & on-prem Azure instances.

Requirements

• squashed commits
• included documentation
• added unit tests and e2e tests (if applicable).

Issue Fixed:

Fixes #444

Does this change contain code from or inspired by another project?

• Yes
• No

If "Yes," did you notify that project's maintainers and provide attribution?

Special Notes for Reviewers:

[aramase]

Thank you for the PR @chrisamert. This change is specific to the cloud env file name. I think instead if we allow mounting arbitrary volumes it'll work for the cloud env file and also for any other required files in the future. WDYT?

Essentially supporting custom volumeMounts and volumes.

[chrisamert]

Thank you for the PR @chrisamert. This change is specific to the cloud env file name. I think instead if we allow mounting arbitrary volumes it'll work for the cloud env file and also for any other required files in the future. WDYT?

Essentially supporting custom volumeMounts and volumes.

@aramase The cloudEnv is the only scenario I know of at the moment that requires a custom volume mount, so I was hesitant to make it a general solution. It also didn't seem like something that was likely to be needed in the future; I don't picture the Pod needing access to host files (beyond the one it mounts itself) a very common scenario. My thought is to leave it specific to the cloud env file as the intent is more clear. I'll leave the ultimate decision up to you all though, if you'd rather see this as a general solution supporting any custom 'volumes' and 'volumeMounts', I can certaintly update this PR with that change.

[chrisamert]

Thank you for the PR @chrisamert. This change is specific to the cloud env file name. I think instead if we allow mounting arbitrary volumes it'll work for the cloud env file and also for any other required files in the future. WDYT?

Essentially supporting custom volumeMounts and volumes.

@aramase I've gone ahead and implemented the custom 'volume' and 'volumeMounts' here. Let me know what you think, I'm fine with either approach

[aramase]

@chrisamert The changes look good. Could you rebase the PR?

[chrisamert]

Done!

[sozercan]

Thank you! LGTM