Allow name collision on interfaces with Stub

[Jooseppi12]

Consider the following interface:

type MyType =
    abstract MyFunc : string -> string
    abstract MyFunc : string seq -> string

The resulting JS should not rename MyFunc to MyFunc_1 to avoid name collision, as we are using this for interop purposes

[Jand42]

Modified ticket name: implementing this change for all Stubs, using the stubInterfaces=true setting is just a special case