Support types in the standard library (#5651)

* Parse an unparse type decls (and refactor impl attributes slightly)

Signed-off-by: Nick Cameron <nrc@ncameron.org>

* Remove special treatment of geometric types from parser and executor

Signed-off-by: Nick Cameron <nrc@ncameron.org>

* Generate docs for std types

Signed-off-by: Nick Cameron <nrc@ncameron.org>

* Hover tool-tips for types and fixup the frontend

Signed-off-by: Nick Cameron <nrc@ncameron.org>

* Fixes

Signed-off-by: Nick Cameron <nrc@ncameron.org>

---------

Signed-off-by: Nick Cameron <nrc@ncameron.org>

rust/kcl-lib/src/execution/memory.rs

@@ -250,6 +250,8 @@ use crate::{
 
 /// The distinguished name of the return value of a function.
 pub(crate) const RETURN_NAME: &str = "__return";
+/// Low-budget namespacing for types.
+pub(crate) const TYPE_PREFIX: &str = "__ty_";
 
 /// KCL memory. There should be only one ProgramMemory for the interpretation of a program (
 /// including other modules). Multiple interpretation runs should have fresh instances.