Backport of UI/add allowed response headers secret mount into release/1.12.x

[hc-github-team-secure-vault-core]

Backport

This PR is auto-generated from #19216 to be assessed for backporting due to the inclusion of the label backport/1.12.x.

WARNING automatic cherry-pick of commits failed. Commits will require human attention.

merge conflict error: POST https://api.github.com/repos/hashicorp/vault/merges: 409 Merge conflict []

The below text is copied from the body of the original PR.

---

Adds allowed_response_headers to mount config for secret engines. docs. Allows things like Last-Modified as a header to be on responses to fetching pki CA/CRLs.

Also updates empty state to include the item type in the message, instead of just 'Secret' for each tab

PKI empty state:

---

transit:

---

### transform: ![Uploading Screenshot 2023-02-16 at 7.49.21 AM.png…]()

---

Overview of commits

• 8f36d0d

[hashicorp-cla]

Thank you for your submission! We require that all contributors sign our Contributor License Agreement ("CLA") before we can accept the contribution. Read and sign the agreement

Learn more about why HashiCorp requires a CLA and what the CLA includes

---

temp seems not to be a GitHub user.
You need a GitHub account to be able to sign the CLA. If you already have a GitHub account, please add the email address used for this commit to your account.

_{Have you signed the CLA already but the status is still pending? Recheck it.}