Instantiate conditional types when providing conditional types

[Andarist]

Fixes #46310

The problem was that in this case there are no inference candidates AND logic is somewhat sensitive to where you put a conditional type in your declaration, see the diff that "magically" make it works:

diff --git a/repro_case.ts b/repro_case.ts
index 7a3795816..f9a7f1918 100644
--- a/repro_case.ts
+++ b/repro_case.ts
@@ -14,9 +14,9 @@ declare function createMachine<
   config: {
     types?: TTypesMeta;
   },
-  implementations: TTypesMeta extends TypegenEnabled
-    ? ActionFunction<{ type: 'test' }>
-    : ActionFunction<{ type: string }>
+  implementations: ActionFunction<
+    TTypesMeta extends TypegenEnabled ? { type: 'test' } : { type: string }
+  >
 ): void;

So why the repro case doesn't work and why this workaround works? The problem is that within getApparentTypeOfContextualType the call to instantiateContextualType doesn't touch this conditional type anyhow (again, cause there are no inference candidates gathered before hand) but the mapType(instantiatedType, getApparentType, /*noReductions*/ true); calls getBaseConstraintOfType(type) and that is returning union like this:

ActionFunction<{ type: "test"; }> | ActionFunction<{ type: string; }>

So the function becomes non-inferrable from that in the same way as in here:

declare function call(fn: ((a: string) => void) | ((a: 'test') => void)): void

call((a) => {
  // oops, implicit any
})

When we use a workaround (moving conditional type further down the road):

ActionFunction<
    TTypesMeta extends TypegenEnabled ? { type: 'test' } : { type: string }
>

Then it becomes:

(ev: TTypesMeta extends TypegenEnabled ? { type: 'test' } : { type: string }) => void

It's a single signature, it's returned fine from getContextualSignature and then contextuallyCheckFunctionExpressionOrObjectLiteralMethod is able to infer from it using inferFromAnnotatedParameters+instantiateSignature (and thus resolve this default param, even though there is no candidate for it)

[Andarist]

this gets superseded by #50994