chore(core): refactor to make all unit tests pass (#6)

_This is the first time I ever messed with helm and is an experiment to show what prevents the tests to pass and how far it still depends on the gitea chart_
### Description of the change

- Deletes a single test that seems to depend directly on gitea
- make all tests pass
- Moves all value accesses from `actions` one level up
- Copies content of the gitea chart required by the existing test
  - Reveals all dependencies that needs to be decoupled
- Fixes readme generation
  - add package.json
  - copy dependent readme section from helm-gitea
- Removes all dependencies
- giteaRootURL is now required to be provided
  - consistency check that this value has been provided
  - added test for consistency failure
- nc command no longer uses an hardcoded dns name and is checked in tests
  - added test
- Copied yamllint from helm-gitea
  - added pnpm lock file exclusion
- Installed pnpm in the workflow
- Updated make unittest command in CI to unittest-helm
### Benefits

The existing tests are passing

### Possible drawbacks

The provision job might still not work.

### Applicable issues

- Fixes #5

### Additional information

The following usage should now deploy
```yaml
existingSecret: "somesecret"
existingSecretKey: "key"

## Specify the root URL of the Gitea instance
giteaRootURL: "http://somedomain:3000"
```
### ⚠ BREAKING

- giteaRootURL is now required to be provided
- Moves all value accesses from `actions` one level up
  - The values.yml had this change without updating tests / dev Readme

Reviewed-on: https://gitea.com/gitea/helm-actions/pulls/6
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Reviewed-by: justusbunsi <justusbunsi@noreply.gitea.com>
Reviewed-by: volker.raschek <markus.pesch@web.de>
Co-authored-by: Christopher Homberger <christopher.homberger@web.de>
Co-committed-by: Christopher Homberger <christopher.homberger@web.de>

.yamllint

@@ -0,0 +1,21 @@
+---
+extends: default
+
+ignore: |
+  .yamllint
+  node_modules
+  templates
+  unittests/bash
+  pnpm-lock.yaml
+
+rules:
+  truthy:
+    allowed-values: ['true', 'false']
+    check-keys: False
+    level: error
+  line-length: disable
+  document-start: disable
+  comments:
+    min-spaces-from-content: 1
+  braces:
+    max-spaces-inside: 2