[GlobalISel] Ensure that translateInvoke adds all successors for inlineasm

The existing code didn't add all necessary successors, which resulted in
disjoint basic blocks. These would end up not being legalized which, in the
best case, caused a fallback only in assert builds.

Here's an example:

https://godbolt.org/z/ndx15Enfj

We also end up getting weird codegen here as well.

Refactoring the code here allows us to correctly attach all successors. With
this patch, the above example gives correct codegen at -O0 with and without
asserts.

Also autogen the testcase to show that we add all the successors now.

Differential Revision: https://reviews.llvm.org/D113437