adding js filters

[jryannel]

JS filters are required for pur JS APIs or mixed JS/TS APIs where the API types are described in the .d.ts files. The advantage of a JS/TS mix is that there is no need for typescript in the toolchain. Types are inferred from a typescript compiler if present and if not, the IDEs will infer the types for coding.

The idea is when we generate code inside an app we can not assume the user uses TS, it might be just a JS app. So to avoid depending on the TS toolchain a JS API with .d.ts files will work in both environments.

Missing

• [x] Documentation
• [x] Remove unused type switches in filters
• [x] Add a proof-of-concept JS template with d.ts support

[jryannel]

• docs will be added when the new docs will go online
• we will leave an unused type switch in
• proof-of-concept template will needed to be added later