Update the `README` setup instructions and Make commands

[Baarsgaard]

I had significant trouble getting started with the development of the Provider due the README.md not being easy to read. And I also found the local testing section using test.local to be difficult at best to make use of.

Changes:

• Refactor README.md.

  • Remove duplicate sections (Cloning and Building).
  • Order and organise everything und the new Development Section/header.
  • Migrate to using the dev_overrides in $HOME/.terraformrc to simplify local testing, especially on existing configurations.
  • Expand on the basic Terraform project example (main.tf).
  • Remove references to unused testacc sub command.
  • Update Golang version from 1.14 -> 1.18 (The one used in the CI)

• Refactor .goreleaser

  • fix YAMLlint errors.
  • hooks.post now calls go install . As part of the new dev_overrides workflow.

• Removed the scripts/local-release.sh as it is no longer used anywhere.

• 3 new GNUmakefile sub-commands.

  • setup Create the $HOME/.terraformrc automatically.
  • dev Skip compiling all versions. and uses go install .
  • clean Delete the $HOME/.terraformrc restoring normal terraform plan/apply behaviour.

[Baarsgaard]

@koushik-swaminathan I seem to have forgotten about this PR. Is this of interest to the project? I personally had a lot of trouble contributing as the Readme was difficult to read and had to use a lot of outside resources to get started.

[koushik-swaminathan]

Hi @Baarsgaard, it's definitely useful for the repository. Let me merge the PR :)