Rename structs, enums and components

[hunger]

This adds renaming of structs... in a limited fashion though: You have to be in the declaration of the component/struct or enum you want to rename.

This PR handles significantly more corner cases than the old component renaming code we used to have and comes with a few more tests to cover those.

Up next and building on this code: Trigger renaming based on any use of any of these types.

[ogoffart]

Please add a test which contains different variation of - and _

[ogoffart]

Looks like i_slint_compiler::parser::identifier_text Only that it normalize _ and -, which i think should be done.

[hunger]

Ah! I was almost sure there was something.... I was looking for something like that starting with parse_ though :-)

[ogoffart]

Also would make sense to have a test that checks that symbols that shouldn't be replace don't get replaces.

enum XyZ { Foo }
struct Abc { Foo: Xyz } 

struct Foo { }

component T1 {
   property <Abc> Foo;
   function f() {
        Foo.Foo  == Xyz.Foo; 
   }
}

component T2 {
  function Foo(Foo: int) { Foo + 1; }
  function F() { Foo() }
}

component T3 {
   Foo := Rectangle { }
}

and so on.