[FIR/NI] Refactor type variable gathering from lambda types

Motivation:
- drop getArguments from type context as a duplicate of getArgumentList
- reduce the number of collection allocations in getAllDeeplyRelatedTypeVariables

Additional minor improvements, test data fixes

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/extensionsWithNonValuableConstraints_1_2.fir.kt

@@ -0,0 +1,17 @@
+// !LANGUAGE: -ExperimentalBuilderInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Base
+
+interface Controller<T> : Base {
+    suspend fun yield(t: T) {}
+}
+
+fun <S> generate(g: suspend Controller<S>.() -> Unit): S = TODO()
+
+suspend fun Base.baseExtension() {}
+
+val test1 = generate {
+    <!INAPPLICABLE_CANDIDATE!>yield<!>("foo")
+    baseExtension()
+}

compiler/testData/diagnostics/testsWithStdLib/coroutines/inference/extensionsWithNonValuableConstraints_1_2.kt

@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 // !LANGUAGE: -ExperimentalBuilderInference
 // !DIAGNOSTICS: -UNUSED_PARAMETER
 
@@ -13,6 +12,6 @@ fun <S> generate(g: suspend Controller<S>.() -> Unit): S = TODO()
 suspend fun Base.baseExtension() {}
 
 val test1 = generate {
-    <!INAPPLICABLE_CANDIDATE!>yield<!>("foo")
+    yield("foo")
     baseExtension()
 }