[FIR] Improve rendering of override related diagnostics

Render symbols completely and add containing declaration.

compiler/testData/diagnostics/tests/annotations/rendering/notImplementedMembers.fir.kt

@@ -15,7 +15,7 @@ interface B {
     fun <T> a(@An arg: @An Int)
 }
 
-<!CONFLICTING_INHERITED_MEMBERS("C; a, a")!>interface C<!> : A, B
+<!CONFLICTING_INHERITED_MEMBERS("C; '@An() fun a(@An() arg: @An() Int): Unit' defined in '/A', '@An() fun <T> a(@An() arg: @An() Int): Unit' defined in '/B'")!>interface C<!> : A, B
 
 @An
 abstract class D {