Add golangci linter to project

[umarhussain15]

Q	A
Bug fix?	no	yes
New feature?	no	yes
API breaks?	no	yes
Deprecations?	no	yes
Related tickets
License	Apache 2.0

What's in this PR?

This PR adds the configuration for golangci-lint into the repository and also configures the Makefile to use the linter with lint and fmt options. The CircleCI config is also updated to use the linter everytime, currently it is configured to only output issues in linting without failing with exit code 1 i.e. it calls make lint-warn

Links

• golangci-lint: https://golangci-lint.run/
• Initial config from External Secrets repo: https://github.com/external-secrets/external-secrets/blob/eea369578d0d715af3962f92c08cb26685acf3eb/.golangci.yaml

Checklist

• [x] User guide and development docs updated (if needed)

To Do

• [x] Switch make fmt to also not exit with error until all linting issues are fixed

[mh013370]

i'll go ahead and merge. risk is low since it's just CI changes.