Discourage use of NT APIs

[tqpcharlie]

Description

As per the linked issue, raw NT APIs are old and mostly obsolete, this PR adds user-facing notifications of that.

Not sure if this "officially" counts as the raw APIs being deprecated, or if this is not meant to be a full on deprecation. Thoughts?
Closes #1828

Meta

Merge checklist:

• Pull Request title is short, imperative summary of proposed changes
• The description documents the what and why
• This PR has been linted.
• If this PR changes behavior or adds a feature, user documentation is updated
• If this PR touches photon-serde, all messages have been regenerated and hashes have not changed unexpectedly
• If this PR touches configuration, this is backwards compatible with settings back to v2025.3.2

[tqpcharlie]

Also not 100% sure if this is something that should just be mentioned in the docs, or if Photon should spit out warnings as well when teams invoke these APIs.

[samfreund]

Also not 100% sure if this is something that should just be mentioned in the docs, or if Photon should spit out warnings as well when teams invoke these APIs.

Warnings would likely be a good idea here.

[tqpcharlie]

Hoping to have this ready in the next day or 2