update Microsoft Teams integration documentation

[lieut-data]

Summary

Updated MS Teams product, technical and security documentation. As part of this, I'm proposing we remove the documentation re: embedded Mattermost to focus on the happy path shipping with Mattermost v10.

Docs Impact

The following 3 pages have been updated via this docs PR:

• Mattermost for Microsoft Teams
• Connect Microsoft Teams to Mattermost
• Collaborate within Microsoft Teams

Page redirects have also been updated to ensure that docs visitors reach a valid destination page.

Ticket Link

Fixes: https://mattermost.atlassian.net/browse/MM-59085

[github-actions[bot]]

Newest code from mattermost has been published to preview environment for Git SHA d3c5eae1ba61f998ac49c20b2c480bdb560205be

[github-actions[bot]]

Newest code from mattermost has been published to preview environment for Git SHA 431a1b689a5d941b842613ace6df6cfaea2e5a87

[github-actions[bot]]

Newest code from mattermost has been published to preview environment for Git SHA 3eafdc6b825b5e91d98a1acd6a56a17808a93c97

[cwarnermm]

@lieut-data - Thank you for identifying and fixing issues on a third docs page (the landing page for this feature). Very much appreciated!

[cwarnermm]

@lieut-data - Feel free to merge this docs PR at your convenience!

[github-actions[bot]]

Newest code from mattermost has been published to preview environment for Git SHA f551328d74818023e3a0f253a01f607950f107eb