fix(eslint-plugin): add type-checked configs to legacy config

[timdeschryver]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/ngrx/platform/blob/main/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Documentation has been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

#5002 introduced type-checked configuration files to the flat config, but didn't include them to the legacy config.

What is the new behavior?

This PR also adds the new configurations to the legacy config.
It also renames a couple of files to be consistent (and correct) with the naming conventions.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

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