Rethink constraints incorporation

Namely, remove incorporation “otherInsideMyConstraint” to eliminate
constraint system redundancy and produce a potentially very large number
 of constructs.
Instead, introduce not so “spreadable” incorporation during variable
fixation (equality constraint with result type into other constraints).
^KT-41644 Fixed
^KT-42195 Fixed
^KT-42920 Fixed
^KT-42791 Fixed
^KT-41741 Fixed

compiler/testData/diagnostics/testsWithStdLib/inference/performance/kt41644.kt

@@ -0,0 +1,44 @@
+// FIR_IDENTICAL
+//!DIAGNOSTICS: -UNUSED_PARAMETER -CAST_NEVER_SUCCEEDS
+
+sealed class DataType<T> {
+    sealed class NotNull<T> : DataType<T>() {
+        abstract class Partial<T> : NotNull<T>()
+    }
+}
+
+class Tuple8<A, DA : DataType<A>, B, DB : DataType<B>, C, DC : DataType<C>, D, DD : DataType<D>, E, DE : DataType<E>, F, DF : DataType<F>, G, DG : DataType<G>, H, DH : DataType<H>>(
+    firstName: String, firstType: DA,
+    secondName: String, secondType: DB,
+    thirdName: String, thirdType: DC,
+    fourthName: String, fourthType: DD,
+    fifthName: String, fifthType: DE,
+    sixthName: String, sixthType: DF,
+    seventhName: String, seventhType: DG,
+    eighthName: String, eighthType: DH
+) : Schema<Tuple8<A, DA, B, DB, C, DC, D, DD, E, DE, F, DF, G, DG, H, DH>>()
+
+class EitherType<SCH : Schema<SCH>>(
+    schema: SCH
+)
+
+open class Schema<T>
+
+fun <A, DA : DataType<A>, B, DB : DataType<B>, C, DC : DataType<C>, D, DD : DataType<D>, E, DE : DataType<E>, F, DF : DataType<F>, G, DG : DataType<G>, H, DH : DataType<H>> either8(
+    firstName: String, firstType: DA,
+    secondName: String, secondType: DB,
+    thirdName: String, thirdType: DC,
+    fourthName: String, fourthType: DD,
+    fifthName: String, fifthType: DE,
+    sixthName: String, sixthType: DF,
+    seventhName: String, seventhType: DG,
+    eighthName: String, eighthType: DH
+): DataType.NotNull.Partial<Either8<A, B, C, D, E, F, G, H>> =
+    EitherType(
+        Tuple8(
+            firstName, firstType, secondName, secondType, thirdName, thirdType, fourthName, fourthType,
+            fifthName, fifthType, sixthName, sixthType, seventhName, seventhType, eighthName, eighthType
+        )
+    ) as DataType.NotNull.Partial<Either8<A, B, C, D, E, F, G, H>>
+
+class Either8<T, U, V, W, X, Y, Z, T1>