Add ESLint to CI

[mspirkov]

Q	A
Is bugfix?	❌
New feature?	❌
Breaks BC?	❌
Fixed issues

The ESLint configuration was added here: #12452
Then Codeclimate was removed here: #20572
It seems that these files are no longer needed. It might be worth adding ESLint in separate request and adding a new configuration for it.

[samdark]

I think ESLint is automatically used by IDEs/editors and the config matches the code style used with Yii2.

[mspirkov]

It seems that this will only work if ESLint is installed globally, as it is not available in this repository. You also need an older version of ESLint that supports this configuration.

I still think that it is necessary to install a new version of ESLint and add a configuration for it. It is also worth adding an ESLint check to the CI

[mspirkov]

I can do it in this PR if it's better.

[mspirkov]

I ran ESLint with the old configuration and got 60 errors in framework/assets. I'll change it a bit so there are no errors.

[mspirkov]

I have reduced the level of these errors and limited their number. It would be great to correct them in the future.

[mspirkov]

@terabytesoftw @samdark Please take another look

[Arhell]

lgtm

[samdark]

👍