Feature: Allow changing default Vault address and Kubernetes mount

[isugimpy]

This PR is a step toward #82 in that it allows setting the Vault address and Kubernetes mount globally, instead of them being set as constants in the code. It does not remove the ability for users to specify vaultAddress or vaultKubernetesMountPath on their SecretProviderClass. This is a big advantage because it allows the cluster operator to set sane defaults for a given cluster that users won't have to be aware of to use the CSI.

[hashicorp-cla]

All committers have signed the CLA.

[isugimpy]

Oh, and just to clarify since I hadn't said so explicitly: I've tested this on a live cluster and everything seems to work as expected.

[tomhjp]

Thanks for raising this! It all looks good to me, it's just raised one existing issue with the flags that I'd like to fix before we add any more with underscores.

Please could you also add a changelog entry? Other than that, I think the test coverage looks good so this is pretty much ready to land.

[isugimpy]

Fixed things up in the requested way. If possible, after this is merged I'd greatly appreciate y'all cutting a release for this. We're wanting to start using this in production, and it'd be super helpful to not have to run a forked binary instead of the official release.

[tomhjp]

Thank you! It shouldn't be long to wait until the next release

[tomhjp]

Apologies I butchered the resolve conflicts step a bit after merging the other open PR, hopefully can get a set of green CI checks and merge this shortly.

[isugimpy]

No worries, greatly appreciate the review and approval!