Demangling: Make demangled names more readable and further reduce the size of the simplified demangled names

The goal here is to make the short demangling as short and readable as possible, also at the cost of omitting some information.
The assumption is that whenever the short demangling is displayed, there is a way for the user to also get the full demangled name if needed.

*) omit <where ...> because it does not give useful information anyway

Deserializer.deserialize<A where ...> () throws -> [A]
--> Deserializer.deserialize<A> () throws -> [A]

*) for multiple specialized functions only emit a single “specialized”

specialized specialized Constructible.create(A.Element) -> Constructible<A>
--> specialized Constructible.create(A.Element) -> Constructible<A>

*) Don’t print function argument types:

foo(Int, Double, named: Int)
--> foo(_:_:named:)

This is a trade-off, because it can lead to ambiguity if there are overloads with different types.

*) make contexts of closures, local functions, etc. more readable by using “<a> in <b>” syntax
This is also done for the full and not only for the simplified demangling.

Renderer.(renderInlines([Inline]) -> String).(closure #1)
--> closure #1 in Renderer.renderInlines

*) change spacing, so that it matches our coding style:

foo <A> (x : A)
--> foo<A>(x: A)

Author: eeckstein

include/swift/Demangling/Demangle.h

@@ -34,7 +34,6 @@ namespace Demangle {
 
 struct DemangleOptions {
   bool SynthesizeSugarOnTypes = false;
-  bool DisplayTypeOfIVarFieldOffset = true;
   bool DisplayDebuggerGeneratedModule = true;
   bool QualifyEntities = true;
   bool DisplayExtensionContexts = true;
@@ -49,6 +48,7 @@ struct DemangleOptions {
   bool ShortenValueWitness = false;
   bool ShortenArchetype = false;
   bool ShowPrivateDiscriminators = true;
+  bool ShowFunctionArgumentTypes = true;
 
   DemangleOptions() {}
 
@@ -68,6 +68,7 @@ struct DemangleOptions {
     Opt.ShortenValueWitness = true;
     Opt.ShortenArchetype = true;
     Opt.ShowPrivateDiscriminators = false;
+    Opt.ShowFunctionArgumentTypes = false;
     return Opt;
   };
 };