feat: add gateway-operator helm chart

[tao12345666333]

What this PR does / why we need it:

Add initial functionality to the gateway-operator Helm chart.

Which issue this PR fixes

(optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged)

• fixes https://github.com/Kong/gateway-operator/issues/1323

Special notes for your reviewer:

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• [ ] PR is based off the current tip of the main branch.
• [ ] Changes are documented under the "Unreleased" header in CHANGELOG.md
• [ ] New or modified sections of values.yaml are documented in the README.md
• [ ] Commits follow the Kong commit message guidelines

[tao12345666333]

How about prepare-kgo-chart?

[rainest]

Yeah, anything is fine, you'll just need to make a PR to main that adds that branch name to https://github.com/Kong/charts/blob/main/.github/workflows/release-pr.yaml#L11-L13

We should arguably rename that file too. It runs tests, not releases. IDK what I was thinking when I renamed it to that.

[tao12345666333]

As an initial submission, I want it to work properly first and then continue adding configuration options.