feat: Add support for relative path for tflint

[MaxymVlasov]

Put an x into the box if that apply:

• This PR introduces breaking change.
• This PR fixes a bug.
• This PR adds new functionality.
• This PR enhances existing functionality.

Description of your changes

tflint: Add relative path support.

Add common functions that will be moved to separately file in the future.
For DRY reason

Relates: #252, #255, #259, #262

How has this code been tested

Run pre-commit run -a for each configuration. Results should be the same.

repos:
- repo: git://github.com/antonbabenko/pre-commit-terraform
  rev: 0f7aa9e92024ed3656954306c327ea563ce0e868
  hooks:
  - id: terraform_tflint
    args:
      - '--args=--config=.tflint.hcl'

repos:
- repo: git://github.com/antonbabenko/pre-commit-terraform
  rev: 0f7aa9e92024ed3656954306c327ea563ce0e868
  hooks:
  - id: terraform_tflint
    args:
      - '--args=--config=__GIT_WORKING_DIR__/.tflint.hcl'

[MaxymVlasov]

@gravitybacklight jfyi

[MaxymVlasov]

Had a conversation with Anton about __GIT_WORKING_DIR__ and found that can be used non-default config names in many subdirectories like

tflint --config other_config.hcl

https://github.com/terraform-linters/tflint/blob/master/docs/user-guide/config.md

So that PR break that and, also, decreases exciting functional.

Maybe, I will investigate GIT_DIR var in the future, as git native replacement for __GIT_WORKING_DIR__. If not - I will add __GIT_WORKING_DIR__ for all hooks

[antonbabenko]

@MaxymVlasov GIT_DIR does not exist in many cases and for many users.

I use this hook in my .bash_profile:

precmd() {
	GIT_REPO_DIR=$(git rev-parse --show-toplevel 2>/dev/null)
	if [[ -n "$GIT_REPO_DIR" ]]; then
	  export GIT_REPO_DIR="$GIT_REPO_DIR"
	fi
}

[yermulnik]

I use this hook in my .bash_profile

jfyi, it should be safe to replace it with a oneliner:

precmd() {
        GIT_REPO_DIR=$(git rev-parse --show-toplevel 2>/dev/null) && export GIT_REPO_DIR || unset GIT_REPO_DIR
}