WIP: remove .eslintrc, use eslint-config-nrf

[IvanSanchez]

This has been prompted by NordicSemiconductor/pc-nrfconnect-launcher#186 (comment) - if the license header is a requirement, why aren't we managing that automatically? Also, why are we copy-pasting .eslintrc files between projects?

This PR is an attempt to provide a solution for both, in the form of a small monorepo and scoped npm packages (to no pollute the @NordicSemiconductor scope at this point). IMO this approach adds the bit of flexibility that nrfconnect-devdep lacks, and is the minimum amount of configuration needed.

[bencefr]

Unfortunately eslint-plugin-notice doesn't seem to be able to match its own template.

[mrodem]

Great improvements! I really like the automatic license insertion on eslint --fix.

The following rule in eslint-config-nrf-react could maybe be moved to an eslint-config-nrf-nrfconnectapp package, as it is only needed for nRF Connect apps:

        "import/no-unresolved": [
            "error",
            {
                "ignore": [ "nrfconnect/.*", "pc-ble-driver-js", "pc-nrfjprog-js", "serialport", "electron" ]
            }
        ],

In such a package, we could maybe also disable react/prop-types only for the index.jsx using a file pattern. This is something we have in the boilerplate's index.jsx now. There are probably some other rules we could add to aid app development.

I see that there are also some duplicate rules in eslint-config-nrf-base and eslint-config-nrf-react. If the intention is that we always want to extend the nrf-base rules, then I believe the duplicates can be removed from the nrf-react package.

[IvanSanchez]

So shall we create a nordicsemi/eslint-config-nrf repo and take it from there?

[bencefr]

I think it's a good idea to take the control and set our rules, I agree to have a repo for this.
For the eslint-plugin-notice I'd suggest to have a looser check maybe only for the first line, since it's broken as it is now.

[kenr]

This is a good idea.

An observation:
nrf-device-lister-js: eslint ^4.16.0
pc-nrfconnect-dev: eslint 3.19.0

Since the eslint configuration file format has changed between v3 and v4 and nrf-device-lister-js will be used from nrfconnect-connect-core which pulls in pc-nrfconnect-devdep, which use v3, I guess this PR will require some work in multiple projects?