[GlobalISel][CallLowering] Look through call parameters for flags

We weren't looking through the parameters on calls at all.

E.g., say you had

```
declare i32 @zext(i32 zeroext %x)

...
%y = call i32 @zext(i32 %something)
...

```

At the point of the call, we wouldn't know that the %something should have the
zeroext attribute.

This sets flags in about the same way as
TargetLoweringBase::ArgListEntry::setAttributes.

Differential Revision: https://reviews.llvm.org/D86125