Keep comments for ts interface generation ✨

[Freymaurer]

I updated ts interface generation to keep xmlDoc comments from f# code. I tried to uphold existing patterns, but please check if everything is fine with you:

The changes transpile the following f# code:

/// This is a user, a very strange individium which will find each and every edge case existing.
[<AllowNullLiteral>]
[<Global>]
type User [<ParamObjectAttribute; Emit("$0")>] (id: int, ?name: string, ?age: int) =
    /// Id used for id stuff
    member val id = id with get, set
    /// name used for naming conventions
    member val name: string option = jsNative with get, set
    /// age because you never tell age
    member val age: int option = jsNative with get, set

to:

/**
 * This is a user, a very strange individium which will find each and every edge case existing.
 */
export interface User {
    /**
     * Id used for id stuff
     */
    id: int32,
    /**
     * name used for naming conventions
     */
    name?: string,
    /**
     * age because you never tell age
     */
    age?: int32
}

I kept the example in src/quicktest/QuickTest.fs.

[ncave]

@Freymaurer Can you also please update the changelog (both in Fable.Cli and Fable.Compiler) with this PR? Thanks!

[Freymaurer]

Is there some contribution guide i can follow or just try to follow the existing patterns?

[MangelMaxime]

Is there some contribution guide i can follow or just try to follow the existing patterns?

Just try to follow the existing convention for this PR it would be something like:

* [TS] Include XML Doc comment on interface properties (by @Freymaurer)

[Freymaurer]

@ncave done!

[ncave]

LGTM

[MangelMaxime]

Thank you