re-instate no-unnecessary-condition eslint rule

[christianvogt]

Fixes https://issues.redhat.com/browse/RHOAIENG-2413

Description

Turns on the @typescript-eslint/no-unnecessary-condition as an error.

How Has This Been Tested?

npm run test:lint

Test Impact

Added new unit test for enum utils.

Request review criteria:

Self checklist (all need to be checked):

• The developer has manually tested the changes and verified that the changes work
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• The developer has added tests or explained why testing cannot be added (unit tests & storybook for related changes)

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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

[pnaik1]

/lgtm

[uidoyen]

/lgtm

[openshift-ci]

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