Replace mocha --opts approach

[Katka92]

Is your task related to a problem? Please describe.

According to the official mocha page, the mocha --opts are going to be deprecated [1]. We should consider changing that approach. When choosing the right way it should be taken into account having some parametrized approach to run test suites.
Currently, if we want to have a new test suite, we need to create a new script in scripts part in package.json file and corresponding mocha-<something>.opts file with the definition. We plan to have a lot of tests for devfiles (default ones and getting-started ones) so using that approach there will be a lot of files in the root and a package.json will grow quite large.
The chosen approach should be easily adoptable by downstream.

[1] https://mochajs.org/#-opts-path

Describe the solution you'd like

There are several ways we can achieve that.

1. Use --config .mocharc.js instead of --opts
   Documentation: https://mochajs.org/#-config-path
   The --config in mocha allows to dynamically compose the structure that was saved in mocha.opts. Having that we can dynamically change parameters and test suites. Basically there will be file mocharc.js with all the logic. [2]

2. Use "parent" test suite class that will combine specified tests
   This approach would require having all test suites exported e.g. as a function. Then the "parent" test suite file can execute only specified ones.

3. Using the environment variables
   We can specify some environment variable that would contain a specific test(s) that should be executed. In package.json there would be just one script working with this parameter and generating suite that would be executed. (Can be done also with --config e.g. using .mocharc.json [3]).

[2] https://github.com/mochajs/mocha/blob/master/example/config/.mocharc.js
[3] https://github.com/mochajs/mocha/blob/master/example/config/.mocharc.json

Describe alternatives you've considered

There can be also other alternatives - those can be also discussed during the investigation part of that issue.

[Katka92]

I've noticed that we are getting the warning in upstream test image:

(node:146) DeprecationWarning: Configuration via mocha.opts is DEPRECATED and will be removed from a future version of Mocha. Use RC files or package.json instead.

[che-bot]

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[Katka92]

/remove-lifecycle stale

[Katka92]

I think the issue was still not solved, so I'm leaving it open.

[che-bot]

Issues go stale after 180 days of inactivity. lifecycle/stale issues rot after an additional 7 days of inactivity and eventually close.

Mark the issue as fresh with /remove-lifecycle stale in a new comment.

If this issue is safe to close now please do so.

Moderators: Add lifecycle/frozen label to avoid stale mode.

[Katka92]

/remove-lifecycle stale

[che-bot]

Issues go stale after 180 days of inactivity. lifecycle/stale issues rot after an additional 7 days of inactivity and eventually close.

Mark the issue as fresh with /remove-lifecycle stale in a new comment.

If this issue is safe to close now please do so.

Moderators: Add lifecycle/frozen label to avoid stale mode.