[FIR] Don't set lambda parameter type to Nothing by default

... when the expected type is not a function type.
Instead set it to a new type variable.
This fixes a bunch of false negative CANNOT_INFER_PARAMETER_TYPE.

#KT-59882 Fixed

compiler/testData/diagnostics/tests/resolve/newLineLambda.fir.kt

@@ -112,6 +112,6 @@ fun testTwoLambdas() {
 fun f1(): (() -> Unit) -> (() -> Unit) -> Unit {
     return <!RETURN_TYPE_MISMATCH!>{ l1 ->
         l1()
-        <!TOO_MANY_ARGUMENTS!>{ l2 -> <!UNRESOLVED_REFERENCE!>l2<!>() }<!>
+        <!TOO_MANY_ARGUMENTS!>{ <!CANNOT_INFER_PARAMETER_TYPE!>l2<!> -> <!UNRESOLVED_REFERENCE!>l2<!>() }<!>
     }<!>
 }

compiler/testData/diagnostics/tests/resolve/overloadConflicts/allLambdas.fir.kt

@@ -1,9 +0,0 @@
-// !DIAGNOSTICS: -UNUSED_PARAMETER
-
-object X1
-object X2
-
-fun <T1> foo(x: T1, f: (T1) -> T1) = X1
-fun <T2> foo(xf: () -> T2, f: (T2) -> T2) = X2
-
-val test: X2 = <!OVERLOAD_RESOLUTION_AMBIGUITY!>foo<!>({ 0 }, { it -> it + 1 })

compiler/testData/diagnostics/tests/resolve/overloadConflicts/allLambdas.kt

@@ -1,4 +1,5 @@
-// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE, -DEBUG_INFO_MISSING_UNRESOLVED
+// FIR_IDENTICAL
 
 object X1
 object X2
@@ -6,4 +7,4 @@ object X2
 fun <T1> foo(x: T1, f: (T1) -> T1) = X1
 fun <T2> foo(xf: () -> T2, f: (T2) -> T2) = X2
 
-val test: X2 = <!OVERLOAD_RESOLUTION_AMBIGUITY!>foo<!>({ 0 }, { <!CANNOT_INFER_PARAMETER_TYPE!>it<!> -> <!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!>it<!> <!DEBUG_INFO_MISSING_UNRESOLVED!>+<!> 1 })
+val test: X2 = <!OVERLOAD_RESOLUTION_AMBIGUITY!>foo<!>({ 0 }, { <!CANNOT_INFER_PARAMETER_TYPE!>it<!> -> it + 1 })