docs: Add License Assignment Docs for Entra

[rexchoppers]

As highly requested, we've tested License Assign via SCIM with Entra (We already have this functionality with Okta) and we're happy to make this publicly known via these documentation updates

Changes:

• Removed any references to License assignment via Entra NOT supported
• Update Entra documentation to include steps on how to assign license via Entra (Pretty much an exact copy of Okta docs) @kostas-localstack Added to the review for technical overview
• Removed any references to Legacy API Key. Confirmed with @Pive01 and we've completely removed this from LocalStack. Small cleanup job

My first docs PR at LocalStack so any feedback is much appreciated

Closes: DOC-411

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[quetzalliwrites]

ty for your contribution @rexchoppers, once you address Kostas' feedback this LGTM :)

Just an FYI, I don't think I see a docs ticket linked to this request. Can you please either create a docs ticket for this PR or share here the url if the docs ticket already exists.

[Pive01]

Left my 2 cents, thanks for the api key cleanup! 💟

[rexchoppers]

ty for your contribution @rexchoppers, once you address Kostas' feedback this LGTM :)

Just an FYI, I don't think I see a docs ticket linked to this request. Can you please either create a docs ticket for this PR or share here the url if the docs ticket already exists.

@quetzalliwrites Done! I had an existing issue that I've moved to the DOC project + reference on PR now