[FEATURE REQUEST] Mark some API methods as safe to retry POST on

[lkubb]

Is your feature request related to a problem? Please describe.
By default, the client does not retry any POST/PATCH requests for good reason.

However, there are some API methods where we can safely retry these requests, for example lookups or unwrapping.

Related: #95

Describe the solution you'd like
Retry POST/PATCH requests on allowlisted paths by default.

Describe alternatives you've considered
Enabling retry_post completely, which can result in unexpected behavior since it's potentially non-idempotent.

Additional context
This is a bit tricky since the VaultRetry instance does not receive URL details. We might need to do it similar to this mockup in saltext.vault.utils.vault.client.VaultClient.request_raw:

if method in ("POST", "PATCH") and endpoint in SAFE_TO_RETRY_POST:
    saved_retry_post, self.session.max_retries.retry_post = self.session.max_retries.retry_post, True
    try:
        # ...
    finally:
        self.session.max_retries.retry_post = saved_retry_post