chore: add golangci-lint config file

[sahidvelji]

This PR

• Add a golangci-lint config file. The linters configured here are the default ones that you see here: https://golangci-lint.run/usage/linters/. In addition to that, I've also enabled the gofmt formatter, which just ensures that code is formatted using go fmt.
• Also introduce a new Makefile target fix, which auto-fixes some linter findings. See this table for linters which support auto-fix: https://golangci-lint.run/usage/linters/

Related Issues

Fixes #360

Notes

https://golangci-lint.run/usage/configuration/

Follow-up Tasks

How to test

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.89%. Comparing base (42e33ba) to head (6c520cb).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #366      +/-   ##
==========================================
+ Coverage   85.75%   85.89%   +0.13%     
==========================================
  Files          20       20              
  Lines        1453     1453              
==========================================
+ Hits         1246     1248       +2     
+ Misses        186      185       -1     
+ Partials       21       20       -1     

Flag	Coverage Δ
e2e	85.89% <ø> (+0.13%)	⬆️
unit	85.89% <ø> (+0.13%)	⬆️

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