Combined Uniquify and LowerTypes pass (#1784)

* Utils: add to_dir helper function

* firrt.SymbolTable trait for scanning declarations

* ir: RefLikeExpression trait to represent SubField, SubIndex, SubAccess and Reference nodes

* add new implementation of the LowerTypes pass

* replace LowerTypes with NewLowerTypes

* remove dependencies on Uniquify

* GroupComponentSpec: GroupComponents is run before lower types

* NewLowerTypes: address Adam's suggestions

* LoweringCompilerSpec: Uniquify was removed and NewLowerTypes

* LowerTypesSpec: add newline at the end of file

* LowerTypesSpec: port Uniquify tests to combined pass

* NewLowerTypes: ensure that internal methods are not visible

* NewLowerTypes: extend DependencyAPIMigration

* NewLowerTypes: lower ports without looking at the body

* LowerTypesSpec: use TransformManager instead of hard coded passes.

* NewLowerTypes: names are already assumed to be part of the namespace

* LowerTypesSpec: test name clashes between ports and nodes,  inst, mem

* NewLowerTypes: correctly rename nodes, mems and instances that clash with port names

* NewLowerTypes: Iterable[String] instead of Seq[String] for 2.13

* NewLowerTypes: add a fast path for ground types without renaming

* LowerTypesSpec: remove trailing commans for 2.11

* LowerTypesSpec: explain why there are two

* Uniquify: use loweredName from NewLowerType

* replace old LowerTypes pass with NewLowerTypes pass

* Uniquify: deprecate pass usage

There are some functions that are still used by other passes.

* LowerTypes: InstanceKeyGraph now has a private constructor

* LowerTypes: remove remaining references to NewLowerTypes

* LoweringCompilerSpec: fix transform order to LowerTypes

* SymbolTable: add improvements from PR

* LoweringCompilerSpec: ignore failing CustomTransform tests