Migration of helm charts into the charts repository

[SrishT]

Description

We intend to move the charts from this repository into a separate one (possibly https://github.com/pravega/charts). The motivation is to finally maintain the charts of all pravega dependencies in the same place (and also keep the published charts in the same place). We however intend to start tis migration from the charts maintained in this repository.
The primary reason for introducing this change is to decouple the charts from their underlying components, so that both these components can be developed and released independently.
We also plan to change the versioning of the charts. Till now we have kept the chart version and the app version in sync, but we want to change that going forward, so that each of these fields are incremented only when required.

Location

charts

Suggestions for an improvement

Changes needed in the charts repository

• migrate all charts into that repository (Migrate all charts from the operator repositories into this repository charts#4)
• move the published charts into a separate branch (Move published charts into a separate branch charts#5)
• separate the chart version from the app version (Separate chart version from app version charts#6)
• add a pull request template within the charts repository which requires proof of manual testing
• define the release process (Define the release process for the charts charts#7)

Changes needed in this repository

• Remove charts from this repository
• Modify the contribution guidelines for users to contribute any changes to the charts along with every relevant PR. It needs to be done as part of a separate PR to the charts repository

Changes needed over time, and not immediately

• adding automated tests for the validation of charts (after every change is introduced)
• automate the release process for the charts