Introduce the latest DVC version extension is tested with

[shcheklein]

Fixes #2063

• Fixes tests (we were not testing properly since we were using join(',') instead of join('.') which gives NaNs ... and NaNs are terrible in JS
• Introduces the variable that defines the latest version of DVC that we know is compatible with. Now if the detected version is between MIN_VERSION and BUILD_VERSION we are not firing any warnings

Things to improve / discuss:

• Name of the variable. Can be TESTED_WITH_VERSION or something. Any thoughts?
• Lifecycle of this variable. Probably we should move it to the package.json, listen to DVC updates and automatically release a new version of the extension (can be done in the future, I guess). For now we can keep an eye and see if that works.
• I'm not familiar with TS - can semver be wrapped to avoid things like NaNs, etc? (minor, I think)

TODO:

• Address feedback
• CodeClimate - see the complaints and fix

[mattseddon]

👍🏻

[qlty-cloud-legacy]

Code Climate has analyzed commit dd95a6b and detected 0 issues on this pull request.

The test coverage on the diff in this pull request is 100.0% (85% is the threshold).

This pull request will bring the total coverage in the repository to 96.7% (0.0% change).

View more on Code Climate.

[julieg18]

Looks good to me!