Type annotations for instruction operands are omitted, e.g.
```
%3 = struct $S(%1, %2)
```
Operand types are redundant anyway and were only used for sanity checking in the SIL parser.
But: operand types _are_ printed if the definition of the operand value was not printed yet.
This happens:
* if the block with the definition appears after the block where the operand's instruction is located
* if a block or instruction is printed in isolation, e.g. in a debugger
The old behavior can be restored with `-Xllvm -sil-print-types`.
This option is added to many existing test files which check for operand types in their check-lines.
To ensure that we do not accept code that would require an existential call argument
to be evaluated prior to the call, don't open existential call
arguments if the generic parameter that would capture the opened
existential type is used in any prior parameter.
Note that code generation currently moves the opening of the
existential call argument outside of the call, which is a compiler bug.
This change ensures that we don't accept code would *require* this
out-of-order evaluation and adds a test so we know when we fix this.
