Test package correctness by trying to build

[aidanheerdegen]

It would be good to check package correctness by trying to build the package as part of a CI check.

This was precipitated by a PR which changed the source URL of a package such that it would not have built correctly with a CI user.

And while this sort of error could be checked for without building the package, there may be other problems that would not be picked up. Especially if there were changes in other packages that might affect the package being changed.

Some problems to consider

1. We only want to build packages that have changed
2. Builds can take a long time

The time taken might mean this is a check we invoke with a ChatOps comment rather than run automatically with every change. Not sure.

[CodeGat]

Seems fair enough to me. The only disadvantage with ChatOps stuff is that it doesn't prevent/allow merging explicitly like a check does.