Add support for debug builds of the fuzzer

[br-lewis]

This adds a new build target to the fuzzer package, build:dev, which will build the fuzzer with a debug configuration. It also renames the prebuild target to prepack because prebuild will run prior to build which means that the call to prebuild will result in the cmake call in build seeing that things are already built and not doing anything.

While this could be handled by a prebuild:dev script that doesn't use --strip, the other problem is that prebuild (the binary, not the script), will look to see if its output tarball already exists and refuses to continue if all you've changed is the build config and no actual code. That's why I chose to have more of this process go through build and left prebuild to be part of our prerelease pipeline.

[br-lewis]

Want to remove some debugging stuff before review but only after I make sure it actually passes CI.

[bertschneider]

LGTM 👍