Add token_path config option

[coignetp]

What does this PR do?

Add token_path config option so the token can be refreshed at each check run

Motivation

Feature request to be able to rotate tokens, vault integration does something similar

integrations-core/vault/datadog_checks/vault/vault.py

Line 320 in 3616496

def renew_client_token(self):

Additional Notes

Password is actually not required

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• PR title must be written as a CHANGELOG entry (see why)
• Files changes must correspond to the primary purpose of the PR as described in the title (small unrelated changes should have their own PR)
• PR must have changelog/ and integration/ labels attached

[alai97]

Looks good pending three copy nits!

[github-actions]

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[sarah-witt]

Looks good, I had one more comment