[MM-58314] [MM-43784] Markdown and file preview in thread list

[Boruus]

Summary

Allowing markdown in thread list (for at mentions, links, and markdown tables) and add of file preview (for text, images, audio, video, pdf, etc).

Ticket Link

https://mattermost.atlassian.net/browse/MM-58314
https://mattermost.atlassian.net/browse/MM-43784

Checklist

• Added or updated unit tests (required for all new features)
• Has UI changes
• Includes text changes and localization file updates
• Have tested against the 5 core themes to ensure consistency between them.

Device Information

This PR was tested on: iPhone 15 Pro, iOS 17.4

Screenshots

before	after

Release Note

Markdown and file preview in thread list

[mattermost-build]

Hello @Boruus,

Thanks for your pull request! A Core Committer will review your pull request soon. For code contributions, you can learn more about the review process here.

Per the Mattermost Contribution Guide, we need to add you to the list of approved contributors for the Mattermost project.

Please help complete the Mattermost contribution license agreement?
Once you have signed the CLA, please comment with /check-cla and confirm that the CLA check is green.

This is a standard procedure for many open source projects.

Please let us know if you have any questions.

We are very happy to have you join our growing community! If you're not yet a member, please consider joining our Contributors community channel to meet other contributors and discuss new opportunities with the core team.

[Boruus]

Hello @Boruus,

Thanks for your pull request! A Core Committer will review your pull request soon. For code contributions, you can learn more about the review process here.

Per the Mattermost Contribution Guide, we need to add you to the list of approved contributors for the Mattermost project.

Please help complete the Mattermost contribution license agreement? Once you have signed the CLA, please comment with /check-cla and confirm that the CLA check is green.

This is a standard procedure for many open source projects.

Please let us know if you have any questions.

We are very happy to have you join our growing community! If you're not yet a member, please consider joining our Contributors community channel to meet other contributors and discuss new opportunities with the core team.

/check-cla

[mattermost-build]

This PR has been automatically labelled "stale" because it hasn't had recent activity.
A core team member will check in on the status of the PR to help with questions.
Thank you for your contribution!

[marianunez]

@Boruus thank you for your contribution. Can you sign the CLA? Seems that is still missing.

[Boruus]

@Boruus thank you for your contribution. Can you sign the CLA? Seems that is still missing.

Hi, sorry for my long response, i've already signed it for webapp mattermost, do I need to sign it again for mobile ?

[enahum]

/check-cla

[abhijit-singh]

@larkox Could you approve the workflow action here - https://github.com/mattermost/mattermost-mobile/actions/runs/10708019777?