[MM-56792] Clarify large plugin upload error

[daveseo901]

Summary

Changes uploadPlugin() in plugin.go to more descriptively handle the error case where an upload plugin exceeds the maximum file upload size prescribed by the server (by default, this maximum is 100 MB). Now, the server will respond with a 413 HTTP status code and an api.plugin.upload.file_too_large.app_error error ID.

Also changes en.json to include an error message, "Uploaded plugin size exceeds limit." with the error ID mentioned above.

Adds tests for this error handling in plugin_test.go. Changes resources.go to symlink plugin_api_tests to facilitate plugin tests. Maybe in the future we should move plugin_api_tests to the standard tests directory?

Ticket Link

Fixes #26245
Jira https://mattermost.atlassian.net/browse/MM-56792

Release Note

Changed server-side logic to return a 413: Request Entity Too Large HTTP status code for a plugin upload that is too large.

Added an api.plugin.upload.file_too_large.app_error error ID.

Added a more descriptive error message, "Uploaded plugin size exceeds limit." for plugin uploads that are too large.

Added plugin_api_tests to the list of symlinked test resources.

[mattermost-build]

Hello @daveseo901,

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.

[mattermost-build]

E2E tests not automatically triggered, because the PR is not in a mergeable state. Please update the branch with the base branch and resolve outstanding conflicts.

[mickmister]

Thanks @daveseo901! LGTM 👍

[hanzei]

/update-branch

[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!

[hanzei]

Hey @daveseo901,

What do you think about my comments above? #26271 (review)

[daveseo901]

Hi @hanzei ,

I added some comments and a question above!

[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!

[hanzei]

@daveseo901 Are you still interested in wrapping up the final comments on this PR? I would love to merge it soon.

[daveseo901]

@daveseo901 Are you still interested in wrapping up the final comments on this PR? I would love to merge it soon.

@hanzei Yes, I will submit the changes later today.

[hanzei]

I really want to merge this PR, so I updated the error message. It no longer include the SiteURL, but instead explains where to find the settings:

[hanzei]

@larkox Please take another look

[hanzei]

/update-branch

[DHaussermann]

Tested and passed

• Confirmed 2 new UI changes
  
  
• Cryptic URL has been removed
  LGTM!

Huge thanks for your help on this @hanzei

[hanzei]

/update-branch