Remove reliance on the Invision DSM import scripts

[kaelig]

Not everyone at Shopify has access to Invision DSM, so let's manage color tokens directly in tokens/colors.yml instead.

[BPScott]

A nice start!

Some extra steps that'd I'd like to see that will help simplify the colors.yml and make it a bit easier to edit:

• Make values in colors.yml use the acutal colors instead of aliases (and then we can remove the whole aliases section at the top). So https://github.com/Shopify/polaris-tokens/pull/66/files#diff-331a823dcc461b72db5ed76f9928f5a5R62 changes from value: '{!color-purple-text}' to value: '#50495a'. Am I missing some other usage of aliases that means we can't do that?
• formats/sketchpalette.js seems to be the only place where "meta.friendlyName" is used. Can we update that file to generate the friendly name based off the name of the token (lodash's startCase might be helpful), and then remove the friendly name from the metadata
• gulpfile.js seems to be the onlyplace where "meta.filter" is used. You mentioned that the filter is generated from the color based on code from https://codepen.io/kaelig/full/jeObGP/. Would it be possible to extract the "guess the filter" code from that pen and use it within the gulpfile so we don't need to store the filter value, and then remove it from the the metadata.

[alex-page]

It would be great to investigate the points @BPScott raised. I am not sure if they are blocking this PR and could be addressed in another one.

[BPScott]

This is good to go.

Regarding my next steps:

• Inlining the aliases changes the output so technically a breaking change (something for v3)
• Deriving the filter is hard as the code used atm is not deterministic so we'd end up with new filter values every time we generate the dist folder which is no good