Enable Explorer. GitOpsSets/Templates pages uses the Explorer by default

[enekofb]

What changed?

1. Turn the explorer on by default.
2. Switch the default GitOpsSet listing endpoint that the UI uses from the OSS querier to the Explorer querier.
3. Switch the default GitOpsTemplates listing endpoint that the UI uses from the Management querier to the Explorer querier.

Why was this change made?

GitOpsSets recently dropped all its own endpoints. Including the "List GitOpSets" endpoint that used the Management Querier.

Now the gitopssets can either use:

1. The OSS querier which has issues w/ multi-tenancy (the current default)
2. The Explorer querier w/ better multi-tenancy support and faster etc etc (the new default set in this PR)

How was this change implemented?

Changes to values.yaml which the user can revert if they need to.

How did you validate the change?

• tilt up, check that gitopssets still work okay

Release notes

( Add me to the next release notes under Highlights section)

Highlights

Explorer enabled by default. GitOpsSets and GitOpsTemplates uses Explorer by default.

Explorer is enabled by default for GitOpsSets and GitOpsTemplates. This improves the pages with:

• Showing GitOpsSets on multiple clusters
• Faster page load and full-text search for enhanced .

You could control where Explorer is enabled via configuration.

By default, this release configuration is:

explorer:
  enabled: true
  enabledFor:
    - gitopssets
    - templates

In case you want to use the old experience, for example for GitOpsTemplates, override the default values with:

explorer:
  enabled: true
  enabledFor:
    - gitopssets

Documentation Changes

Other follow ups

[foot]

Nice one ⭐ , great PR description.