LT: make where clause with errors parsing same as with PSI

- do not fail on the missing terms
- propagate invalid name to avoid reporting dangling constraints

#KT-58455 fixed

compiler/testData/diagnostics/tests/generics/whereClauseSyntax.fir.kt

@@ -0,0 +1,6 @@
+// DIAGNOSTICS: -DEBUG_INFO_MISSING_UNRESOLVED
+interface I
+fun <E> foo() where E: I {}
+fun <E> fooE1() where <!SYNTAX!><!>: I {}
+fun <E> fooE2() where E: <!SYNTAX, SYNTAX!><!>{}
+fun <E> fooE3() where <!SYNTAX!><!>{}

compiler/testData/diagnostics/tests/generics/whereClauseSyntax.kt

@@ -0,0 +1,6 @@
+// DIAGNOSTICS: -DEBUG_INFO_MISSING_UNRESOLVED
+interface I
+fun <E> foo() where E: I {}
+fun <E> fooE1() where <!SYNTAX!><!>: I {}
+fun <E> fooE2() where E: <!SYNTAX!><!>{}
+fun <E> fooE3() where <!SYNTAX!><!>{}