[MM-84] Update plugin with respect to phase 1 upgrades

[ayusht2810]

Summary

Updated plugin with respect to phase 1 upgrades

• Updated build folder to sync with starter template
• Updated package in go modules to use https://pkg.go.dev/github.com/mattermost/mattermost/server/public
• Updated Makefile
• Updated developer docs link in the readme file

Ticket Link

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (0a59459) 22.82% compared to head (9618c44) 22.82%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #50   +/-   ##
=======================================
  Coverage   22.82%   22.82%           
=======================================
  Files          10       10           
  Lines        1025     1025           
=======================================
  Hits          234      234           
  Misses        784      784           
  Partials        7        7           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[hanzei]

I'm surprised to see us updating this plugin. It's not mentioned in https://forum.mattermost.com/t/upcoming-product-changes-to-boards-and-various-plugins/16669, does that mean we continue to work on it?

@mickmister might know more.

[amwolff]

I lost track of the development work that has been happening on this plugin 1-2 years ago (I'm sorry about that—life's been busy). Has the plugin been useful to anyone/to Mattermost? Is there anything I can help with in case you decide to keep maintaining the plugin?