Add EE license check

[larkox]

Summary

Add license check on plugin activate.

IMPORTANT: This require v5.24.0 of mattermost-server which is not yet released. Therefore, the package cannot be imported, and go.sum has not been properly updated. Probably this PR needs an update when v5.24.0 is in place.

Ticket Link

None

[hanzei]

Could some commit on master be used instead?

[larkox]

This was discussed on a different conversation. We will point to master, merge this, and whenever 5.24 is addressable, we will update the plugin to address the correct server version.

[hanzei]

FYI: https://github.com/mattermost/mattermost-server/releases/tag/v5.24.0-rc1 can be used

[codecov-commenter]

Codecov Report

Merging #151 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #151   +/-   ##
=======================================
  Coverage   23.51%   23.51%           
=======================================
  Files          62       62           
  Lines        2513     2513           
=======================================
  Hits          591      591           
  Misses       1848     1848           
  Partials       74       74           

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[larkox]

@aaronrothschild according to this conversation we discussed about checking for LDAP until we start using 5.24. Should that check be done in this PR?

[DHaussermann]

I tested this.
TE: Plugin fails to start
E0: Plugin fails to start
E10 : Plugin fails to start
E20: Plugin start fine
Based on code change only start up is affected so there is no need to regression test any specific functionality.

When it does not start the following is logged: You need a Enterprise License to activate this plugin

@aaronrothschild

1. Can you just confirm that this will only work with E20 and not E10 as well (Just santiy check :) )
2. given that is E10 only should we clarify the message in the log.

[larkox]

Regarding the log message, what about You need a Enterprise License (E20) to activate this plugin?

[DHaussermann]

Tested and passed

• This is working as expected.
• Change suggestion above has been implemented