feat: add action to publish charts to a website

[gitcommitshow]

Description of the change

Enables better installation experience by being able to install helm charts without cloning the repo.

Solution: Publish charts to a public website hosted on GitHub pages using the release-chart action which then can be installed by following commands

helm repo add rudderstack https://rudderlabs.github.io/helm-charts
helm install my-transformer rudderstack/transformer
helm install my-postgresql rudderstack/postgresql

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklists

• Propose this new deployment
• POC and evaluate maintenance pros/cons
• Final code ready to review

Related issues

Fixes #68

Development

• Lint rules pass locally
• The code changed/added as part of this pull request has been covered with tests
• All tests related to the changed code pass in development

Code review

• This pull request has a descriptive title and information useful to a reviewer. There may be a screenshot or screencast attached
• "Ready for review" label attached to the PR and reviewers mentioned in a comment
• Changes have been reviewed by at least one other engineer
• Issue from task tracker has a link to this pull request

[gitcommitshow]

Tested the installation with following commands

helm repo add rudderstack https://gitcommitshow.github.io/rudderstack-helm/ 
# Test deployment url. After deployment on this repo, the url will be https://rudderlabs.github.io/rudderstack-helm
helm install transformer rudderstack/transformer --set rudderWorkspaceToken="secret"

but it failed on local with following error

Error: INSTALLATION FAILED: template: transformer/templates/deployment.yaml:17:20: executing "transformer/templates/deployment.yaml" at <.Values.global.imagePullSecrets>: nil pointer evaluating interface {}.imagePullSecrets

This has something to do with the not having a default value for imagePullSecrets. Will need to figure out what can we do about it.

[gitcommitshow]

Error: INSTALLATION FAILED: template: transformer/templates/deployment.yaml:17:20: executing "transformer/templates/deployment.yaml" at <.Values.global.imagePullSecrets>: nil pointer evaluating interface {}.imagePullSecrets

To fix this error, I tried an additional param --set global.imagePullSecrets=[] in helm install command. But this results in a different error

Error: INSTALLATION FAILED: 2 errors occurred:
	* Service "transformer-rudderstack" is invalid: spec.ports[0].port: Invalid value: 0: must be between 1 and 65535, inclusive
	* Deployment in version "v1" cannot be handled as a Deployment: json: cannot unmarshal string into Go struct field PodSpec.spec.template.spec.imagePullSecrets of type []v1.LocalObjectReference