ci: changed the way CI works

Squashed commit of the following:

commit b439b895b4ea18fc63124fb66b55b439f7b10fef
Author: Vasek Sraier <git@vakabus.cz>
Date:   Thu Apr 22 19:47:48 2021 +0200

    ci: npm global install in dev container

commit c3a896269b222a8d23af54910ed2fe98193fa496
Author: Vasek Sraier <git@vakabus.cz>
Date:   Thu Apr 22 19:12:12 2021 +0200

    ci: installing npm dependencies globally

commit 473fbf4878c40f859b4bb2eb25c9ccd2ac5a427d
Author: Vasek Sraier <git@vakabus.cz>
Date:   Thu Apr 22 18:56:57 2021 +0200

    scripts: virtual env or ci detection

commit fcf1d0e8035825fc1bd236b9c84bf792198c2aab
Author: Vasek Sraier <git@vakabus.cz>
Date:   Thu Apr 22 18:48:41 2021 +0200

    scripts: fixed bash options

commit aa96cf925ac0cd6ad36b89f011e449006dd6d8e9
Author: Vasek Sraier <git@vakabus.cz>
Date:   Thu Apr 22 18:45:49 2021 +0200

    ci: updated check stage definition

commit 40a00e1261cf51c8a15e237e73d9a1dd2ffd3e61
Author: Vasek Sraier <git@vakabus.cz>
Date:   Thu Apr 22 18:33:51 2021 +0200

    ci: fix dev container definition

commit ccedf3e18aead5097bec11384c2fd08c783129cd
Author: Vasek Sraier <git@vakabus.cz>
Date:   Thu Apr 22 18:30:37 2021 +0200

    ci: fixed typo in .gitlab-ci.yml

commit eaada4a0cfe1282fd90af838f6d2dade0129c47e
Author: Vasek Sraier <git@vakabus.cz>
Date:   Thu Apr 22 18:06:39 2021 +0200

    ci: use different container and always build it