Do not promote struct field with type mistmatch. (#20085)

Do not promote struct field with type mistmatch. (#20085)

* Add a test that reads int field as double.

It fails in `void CodeGen::genCodeForStoreInd(GenTreeStoreInd* tree)`  on `assert(!varTypeIsFloating(targetType) || (targetType == data->TypeGet()));`.

* Fix for the previous test.

No asm diffs.

* Add a test that reads struct field as another struct type.

It fails with assert `Compiler::StructPromotionHelper::CheckFakedType` `assert(fakedFieldsMap.Lookup(fieldHnd));`.

* Fix the previous test.

Check that we promote with the same class.

* Add a test case for accessing an invalid offset.

It fails in `fgMorphStructField` with `noway_assert(fieldLclIndex != BAD_VAR_NUM);`.

* Fix the previous test.

Reject field promotion if offset is invalid. No asm diffs.