Mangle exported symbols

[mjbvz]

Porting #180462 to a branch in our main repo

For #180461. This prototype tries to mangle exported functions, constants, and classes

Current total savings: 1910kb
New total savings: 4077kb

[mjbvz]

Finally got a successful full build: https://dev.azure.com/monacotools/Monaco/_build/results?buildId=215714 Main issue was that I was accidentally mangling ambient type declarations, which messed up some referenced libraries in remote scenarios (this was tricky to track down because it only happens in full builds, not in OSS)

Local testing all seems ok although I haven't run though every scenario. Will continue testing and hopefully get this merged in June

[jrieken]

@mjbvz Can you share numbers how much slower the (product) build will be because of this?

[mjbvz]

@jrieken This makes the compile step of the build about 10 minutes slower: going from 13 minutes to 22 minutes. The other builds steps are not effected

This slow down is due to the large number of rename requests we make against typescript. I brought this up to the TS team but they seem unlikely to address it (the rational being that renames are typically triggered only by occasional UI actions). I also use worker threads to improve performance, but can only use two workers at the moment to avoid memory issues on the CI machines

[jrieken]

fyi @alexdima - you were wondering about the additional costs of this