[FIR] Fix invalid diagnostic fir node sites and improved invalid type parameters count diagnostic report

compiler/testData/diagnostics/tests/cast/bare/ErrorsInSubstitution.fir.kt

@@ -3,7 +3,7 @@
 interface B<T>
 interface G<T>: B<T>
 
-fun f(p: <!UNRESOLVED_REFERENCE!>B<Foo><!>): Any {
+fun f(p: B<<!UNRESOLVED_REFERENCE!>Foo<!>>): Any {
     val v = p as G
     return checkSubtype<G<*>>(v)
 }

compiler/testData/diagnostics/tests/cast/bare/UnrelatedColon.fir.kt

@@ -4,4 +4,4 @@
 interface Tr
 interface G<T>
 
-fun test(tr: Tr) = <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><G>(tr)
+fun test(tr: Tr) = <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><<!WRONG_NUMBER_OF_TYPE_ARGUMENTS!>G<!>>(tr)