chore(acr): fix dev page and update rhdh theme (dev dependency)

[christoph-jerolimov]

Hey, I just made a Pull Request!

1. Fix the dev page in general by adding the missing app-config.yaml (added one from a new backstage app)
2. Changed the dev page to contain also a page header and tabbar, so that it looks like an entity details page
3. Updated the rhdh-theme dev dependency (which is also just used in that dev page)

I don't added a changeset because it doesn't update the plugin itself.

To test the dev page:

cd workspace/acr
yarn install
cd plugins/acr
yarn start

Without the app-config.yaml it was broken.

With the app-config.yaml, but without the Page, Header and TabbedLayout it looked like this:

Finally, with this change, it looks now like this:

✔️ Checklist

• A changeset describing the change and affected packages. (more info)
• Added or updated documentation
• Tests for new functionality and regression tests for bug fixes
• Screenshots attached (for UI changes)
• All your commits have a Signed-off-by line in the message. (more info)

[backstage-goalie]

Missing Changesets

The following package(s) are changed by this PR but do not have a changeset:

• @backstage-community/plugin-acr

See CONTRIBUTING.md for more information about how to add changesets.

Changed Packages

Package Name	Package Path	Changeset Bump	Current Version
@backstage-community/plugin-acr	workspaces/acr/plugins/acr	none	v1.8.5

[christoph-jerolimov]

@invincibleJai @debsmita1 @divyanshiGupta, can one of you test and lgtm this small change?

[ciiay]

lgtm

Thank you 👍

[ciiay]

LGTM

[invincibleJai]

Thanks @christoph-jerolimov , verified the changes

Before:

After:

[invincibleJai]

/lgtm
/approve