[MM-232] Update plugin with respect to phase 1 upgrades

[ayusht2810]

Summary

Updated plugin with respect to phase 1 upgrades

• Updated go version from 1.12 to 1.21
• 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 version in nvmrc file and update package-lock.json file.
• Added base setup for typescript
• Added base setup for test cases
• Fix lint errors
• Updated developer docs link in the readme file

Ticket Link

[codecov-commenter]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (b60a4e9) 15.03% compared to head (66c0e24) 15.22%.

Files	Patch %	Lines
server/utils.go	72.72%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #129 +/- ## ========================================== + Coverage 15.03% 15.22% +0.18% ========================================== Files 13 12 -1 Lines 2301 2306 +5 ========================================== + Hits 346 351 +5 Misses 1936 1936 Partials 19 19 ```

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