[cli][gradle] Adds package name as a global option

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Description of the PR

Extending on #2429, this adds package name globally in the CLI and Gradle Plugins. We have options for api package, model package, and invoker package globally. Configuring the three of these plus packageName in different locations can be confusing for the generators which support all four options.

There may be concern that packageName is made a "global" option and isn't supported by all generators, but there are quite a few options that aren't supported by many generators (e.g. all package related options, file post processing, etc). This favors usability in these cases.

I've opened #2556 for discussions about options which may or may not belong globally.