TypeScript support, + danger.d.ts, + danger DSL change

[orta]

Adds support for dangerfile.ts and uses the Jest config system to handle transformation.

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Previous notes:

This PR started small, but had a while to do some work on the trainf, so I programmed away.

This provides the initial basic setup for TypeScript. I added a test but it is way slow, 41 seconds.

So this will fail. The fail does lead to an interesting culprit for why It is slow though:

I think when we load up Babel or TypeScript then every JS file is sent through babel including all node_modules - which could definitely slow it down. This is likely something inside the Jest env, that should be pretty easy to track down.

[deecewan]

I'm assuming that this references #169?

[orta]

Yeah #169 mainly, I've used up my computer time for today on #174 - but will probably start going over this again in the next few days

[orta]

Note to self, process.execSync can be used to run a child process synchronously. For our Dangerfile.

[codecov-io]

Codecov Report

Merging #172 into master will not change coverage.
The diff coverage is 0%.

@@          Coverage Diff          @@
##           master   #172   +/-   ##
=====================================
  Coverage       0%     0%           
=====================================
  Files           3      4    +1     
  Lines          93     96    +3     
  Branches       17     15    -2     
=====================================
- Misses         93     96    +3

Impacted Files	Coverage Δ
source/commands/danger-pr.ts	0% <0%> (ø)	⬆️
source/commands/danger-run.ts	0% <0%> (ø)	⬆️
...e/runner/_tests/fixtures/__DangerfileTypeScript.ts	0% <0%> (ø)

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[orta]

Alright, I think this should be good to go from the typescript support side. I'd like reviews around that.

I'd like to continue working on this PR specifically on two things, making Circle CI use a dangerfile.ts and adding a Dangerfile rule about ensuring the d.ts in the repo is completely up to date.

[orta]

OK, the circle CI dangerfile is 👍

Fixes #84

[orta]

Our current setup makes it possible for the circle ci danger to pass, and to delete the current message on a PR.

This can be fixed by either #162 or the Danger ID thing discussed in #166

[orta]

green!