chore: run TSLint on all folders

[felixfbecker]

Closes #64

To fix:

ERROR: /Users/felix/src/github.com/sourcegraph/browser-extensions/chrome/extension/background.tsx[114, 1]: Promises must be handled appropriately
ERROR: /Users/felix/src/github.com/sourcegraph/browser-extensions/chrome/extension/background.tsx[268, 5]: Promises must be handled appropriately
ERROR: /Users/felix/src/github.com/sourcegraph/browser-extensions/chrome/extension/background.tsx[276, 5]: Promises must be handled appropriately
ERROR: /Users/felix/src/github.com/sourcegraph/browser-extensions/chrome/extension/background.tsx[321, 5]: Promises must be handled appropriately
ERROR: /Users/felix/src/github.com/sourcegraph/browser-extensions/extension/safari/StorageArea.ts[65, 40]: Explicit type parameter needs to be provided to the constructor
ERROR: /Users/felix/src/github.com/sourcegraph/browser-extensions/extension/storage.ts[91, 40]: Avoid referencing unbound methods which may cause unintentional scoping of 'this'.
ERROR: /Users/felix/src/github.com/sourcegraph/browser-extensions/extension/storage.ts[91, 50]: Avoid referencing unbound methods which may cause unintentional scoping of 'this'.

[felixfbecker]

@ijsnow can you confirm TSLint is now run on all folders?

[ijsnow]

@felixfbecker https://sourcegraph.com/github.com/sourcegraph/browser-extensions@master/-/blob/package.json?diff=ffb64d67db79b099c7879353fdaebfbf2b06194a&utm_source=firefox-extension#L14

[felixfbecker]

So that is a no

[ijsnow]

It's ran on all code that is ran by the browser extension

[felixfbecker]

Tests in cypress/, the webpack configs in webpack/ and the scripts in scripts/ are all TypeScript and should be linted too

[chrismwendt]

Here's how to move this PR to https://github.com/sourcegraph/sourcegraph/tree/master/packages/browser-extensions

cd browser-extensions
git format-patch master --stdout > /tmp/patch

cd ../sourcegraph
cat /tmp/patch | git am -3 --directory=packages/browser-extensions/
# and fixup merge conflicts