[FIR] take ready implicit unit type instead of return type calculation

and assert that symbol is not a substitution/intersection override
in the `compute` method otherwise.

Because `fakeOverrideSubstitution` should be calculated for all real
implicit types, no call to this method should actually happen.

Otherwise, it can be problematic to create a session
which would contain the full designation path:
`provider.getFirCallableContainerFile(symbol)`
returns `firFile` of a super class which might be from module `a`,
when declaration and its outer classes are from module `b`.

^KTIJ-24105

analysis/analysis-api-fe10/tests-gen/org/jetbrains/kotlin/analysis/api/fe10/test/cases/generated/cases/components/callResolver/Fe10IdeNormalAnalysisSourceModuleResolveCallTestGenerated.java

@@ -784,6 +784,12 @@ public class Fe10IdeNormalAnalysisSourceModuleResolveCallTestGenerated extends A
         runTest("analysis/analysis-api/testData/components/callResolver/resolveCall/smartCastImplicitExtensionReceiver.kt");
     }
 
+    @Test
+    @TestMetadata("substituteOverrideResolution.kt")
+    public void testSubstituteOverrideResolution() throws Exception {
+        runTest("analysis/analysis-api/testData/components/callResolver/resolveCall/substituteOverrideResolution.kt");
+    }
+
     @Test
     @TestMetadata("superTypeCallEntryResolveToCallInfo.kt")
     public void testSuperTypeCallEntryResolveToCallInfo() throws Exception {