feat: Machine Token Docs

[Ben2W]

Note to reviewer:
There is not too much content, however I did restructure the docs which is why there are 61 files changed
Let me know if you want me to go about this PR in a different way (ie splitting the PR up or not changing the links around or maybe only change the manifest.json to make it appear the structure was changed, without affecting the links?)

Currently all customer-facing tokens are session tokens. We are adding machine tokens which is another customer-facing token. This PR adds documentation on:

• Understanding machine tokens
• Creating machine tokens
• Using machine tokens to authenticate requests
• authenticating requests with machine tokens.

Additionally because now, all backend requests may no longer have a user + session associated with them, I modified the structure of some of the docs pages, and slightly edited existing pages to help fit the concept of "machine authentication". Read below to see what I changed.

Created the following machine request pages:

/docs/machine-requests/overview
/docs/machine-requests/machine-tokens
/docs/machine-requests/manual-jwt

Moved most of the "Backend Requests" pages to "Session Requests"

Calling this section "backend request" is confusing because machine requests are also backend requests.

This caused most of the "files changed" in the PR because a lot of links were changed from @NWylynko's script.

Old Path	New Path
/docs/backend-requests/overview	/docs/session-requests/overview
/docs/backend-requests/making/same-origin	/docs/session-requests/making/same-origin
/docs/backend-requests/making/cross-origin	/docs/session-requests/making/cross-origin
/docs/backend-requests/making/custom-session-token	/docs/session-requests/making/custom-session-token
/docs/backend-requests/making/jwt-templates	/docs/session-requests/making/jwt-templates
/docs/backend-requests/handling/go	/docs/backend-requests/handling/go
/docs/backend-requests/handling/ruby-rails	/docs/backend-requests/handling/ruby-rails
/docs/backend-requests/handling/manual-jwt	/docs/backend-requests/handling/manual-jwt
/docs/backend-requests/resources/session-tokens	/docs/backend-requests/session-tokens

Some pages that were in "Backend Requests" didn't fit under "Session Requests," so they were moved to their own section:

Old Path	New Path
/docs/backend-requests/versioning/overview	/docs/versioning/overview
/docs/backend-requests/versioning/available-versions	/docs/versioning/available-versions
/docs/backend-requests/resources/rate-limits	/docs/resources/rate-limits

Modified the following pages to add the concept of machine authentication:

Old Docs Page	New Docs Page
https://clerk.com/docs/references/nextjs/auth	https://clerk.com/docs/pr/1725/references/nextjs/auth
https://clerk.com/docs/references/backend/authenticate-request	https://clerk.com/docs/pr/1725/references/backend/authenticate-request
https://clerk.com/docs/references/backend/types/auth-object	https://clerk.com/docs/pr/1725/references/backend/types/auth-object

Slack thread:
https://clerkinc.slack.com/archives/C01QFRQNHSN/p1738141182851989

Checklist

• [ x ] I have clicked on "Files changed" and performed a thorough self-review
• [ x ] I have added the "deploy-preview" label and added the preview link(s) to this PR description
• All existing checks pass

[github-actions]

Hey, here’s your docs preview: https://clerk.com/docs/pr/1725

[github-actions]

Hey, here’s your docs preview: https://clerk.com/docs/pr/1725