Update licenses, add chart keyword and update descriptions

[AlexMapley]

Background

RStudio has rebranded to Posit, and over time we're migrating our code to reflect that. This PR is a small step towards that migration for our helm charts, just updating some behind the scenes things.

Summary

• Update helm chart licenses
• Adds the posit keyword to all helm charts for better search-ability
• Update casing in charts/rstudio-library/Chart.yaml description

Notes

We're failing a linting ci job because i haven't bumped up the chart versions, i'm going to ignore that for now. I don't intend to bump the chart versions with these changes

[AlexMapley]

This PR is still completely valid and i'd like to merge. I don't think we should bump up the chart version for these changes, but we're going to continue to fail our Lint and Test Charts step until we do. I'd like to bypass branch protections for this merge instead, and leave our chart versions unchanged.