Add QuickJS engine

[nrigaudiere]

https://bellard.org/quickjs/

Main advantages:

• small (binary size)
• light (ressources)
• easy to embed (in C)
• good coverage of JS standard (ES2020), including modules
• quite fast for a simple interpreter (2x times slower than v8 without JIT, QuickJS Benchmark)

It does not support ECMA402 (Internationalisation APIs).

The idea is to use QuickJS as the default JS engine, at least for the open source version.

[nrigaudiere]

https://github.com/Browsercore/jsruntime-lib/tree/quickjs