add env var to support rhods-dashboard for dev:start:ext

[christianvogt]

https://issues.redhat.com/browse/RHOAIENG-6597

Description

When using npm run start:dev:ext, it was not possible to target an external cluster running RHOAI.

This change simply adds support for the ODH_APP env variable which can be supplied in the .env.local file. The default value remains odh-dashbaord but can be overridden to rhods-dashboard.

How Has This Been Tested?

Update .env.local to include:

OC_PROJECT=redhat-ods-applications
ODH_APP=rhods-dashboard

oc login ... to your cluster running RHOAI (use a cluster admin)
npm run start:dev:ext

Visit http://localhost:4010 to check the UI is running as expected.

Test Impact

Request review criteria:

Self checklist (all need to be checked):

• The developer has manually tested the changes and verified that the changes work
• Commits have been squashed into descriptive, self-contained units of work (e.g. 'WIP' and 'Implements feedback' style messages have been removed)
• Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• The developer has added tests or explained why testing cannot be added (unit or cypress tests for related changes)

If you have UI changes:

• Included any necessary screenshots or gifs if it was a UI change.
• Included tags to the UX team if it was a UI/UX change (find relevant UX in the SMEs section).

After the PR is posted & before it merges:

• The developer has tested their solution on a cluster by using the image produced by the PR to main

[lucferbux]

/lgtm

Tested, it looks great!

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lucferbux

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [lucferbux]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment