[Core] JavaScript Engine - ESM

[ThuF]

Reconsider the decision to be able to execute ES6 content inside *.js files. It seems that there is a difference in the eval of the content:

• *.js files are evaluated each time.
• *.mjs files are evaluated only once.
• Also there is a difference between the semantics of the two file types.

This doesn't lead to a difference in the performance (e.g. faster execution time, memory consumption, etc.), but could lead to a difference in the behaviour (e.g. content being cached inside *.mjs files).

Impacted areas:

• TypeScript compilation - should result into *.mjs files instead of *.js files