Remove `pick` function

[jrieken]

This should be removed:

vscode/src/vs/base/common/arrays.ts

Line 649 in 6cdea9e

export const pick = <TObject, TKeyName extends keyof TObject>(

Because it make us write property names as strings, e.g pick('bar')(obj) instead of just obj.bar which is bad because

• it gives TS tooling a hard time, e.g find all references, rename, etc pp do not work
• it seems like bloat and not the simplest thing that you can write
• it makes the code impossible to be minified