Allow opening files outside of the file system in viewer

[juliusknorr]

Some early PoC for displaying text file attachments from mail in viewer

• requires Support opening and comparing versions in viewer server#39171
• requires feat: Compare files side by side viewer#1835
• BUG variables css missing
• Properly check if the file outside of the filesystem was passed
• Wrap logic into dedicated component to handle styling
  • Needs a scroll area
  • Header style is missing with blue bar
• BUG: When opening a file in mail the file name is not displayed properly (probably something for mail/viewer) -> needs retesting

Follow up / separate

• Fix menubar size calculation when showing side by side comparison fix: Use resize observer to calculate menubar icon limit #4637
• Cypress tests
• Read only mode does not have syntax highlighting (probably needs moving hljs styles from Editor.vue to prosemirror.scss)

cc @ChristophWurst

[cypress]

2 flaky tests on run #11554 ↗︎

0

149

2

0

2

Details:

Allow opening files outside of the file system in viewer
Project: Text	Commit: b35a36968c
Status: Passed	Duration: 03:39 💡
Started: Aug 7, 2023 5:17 PM	Ended: Aug 7, 2023 5:21 PM

  SyncServiceProvider.spec.js • 1 flaky test

View Output Video

Test		Artifacts
Sync service provider > recovers from a dropped message		Output Screenshots

  UsersApi.spec.js • 1 flaky test

View Output Video

Test		Artifacts
The user mention API > fetches users with valid session		Output Screenshots

_{This comment has been generated by cypress-bot as a result of this project's GitHub integration settings.}

[juliusknorr]

I've updated the checklist above, when giving it another test run together with the versions PR i think there are a few more topics to address, added to the description.

[juliusknorr]

@ChristophWurst FYI we will merge and backport this for 27.1. Iirc you had a mimetype filter in mail so might be a quick win to enable preview for markdown attachments then

[max-nextcloud]

Just a minor remark. Other than that... good to go from my side.

[juliusknorr]

/compile

[mejo-]

/backport 246f158,67f01011cd16b62d153a8593bc49fc55b3c10b20,b35a36968cc33270502133fb44d0a187864b7d4e to stable27

[backportbot-nextcloud]

The backport to stable27 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable27
git pull origin stable27

# Create the new backport branch
git checkout -b fix/foo-stable27

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts. Resolve them.
git cherry-pick abc123

# Push the cherry pick commit to the remote repository and open a pull request
git push origin fix/foo-stable27

More info at https://docs.nextcloud.com/server/latest/developer_manual/getting_started/development_process.html#manual-backport