Add files for git & gitkraken + update php (#479)

* feat(git): add .gitk & .gitignore

References:
- .gitconfig: https://git-scm.com/docs/git-config#SCOPES
- .git-credentials: https://git-scm.com/docs/git-credential-store#FILES
- .gitignore: https://git-scm.com/docs/gitignore#_synopsis
- .gitk: https://git-scm.com/docs/gitk#_files

* feat(gitkraken): add .gk

References:
- .gk
  - Issue: https://github.com/gitkraken/vscode-gitlens/issues/3660
  - PR: https://github.com/gitkraken/vscode-gitlens/pull/3904
  - Implementation (v17.1.1): https://github.com/gitkraken/vscode-gitlens/blob/v17.1.1/src/env/node/gk/localSharedGkStorageLocationProvider.ts#L33

* feat(php): update .php_history

References:
- .php_history: https://www.php.net/manual/en/migration84.new-features.php#migration84.new-features.readline