Various improvements

[TheDauntless]

I updated the script a bit to fit my use cases. I did it in such a way that it doesn't break any of the original API / functionality. Let me know if you want separate PRs for everything, or if you don't like a specific change.

Modifications:

• Added an --extract-only option. When enabled, the apk will be pulled and combined, but not signed, no objection, no AndroidManifest modification and no re-push
• Moved the checkDependencies function to only be called when needed. There's also a small split up depending on what the script is going to do
• Added aapt as dependency for objection injection
• If --extract-only is called, the pulled apk will be saved as <packagename>.apk
• If --save-apk is specified, the --save-apk name will be used for --extract-only
• Small description update to note that this tool supports split apks. It's difficult to find a tool that supports this and that could definitely be the main selling-point
• Added ctrl+c handler. Probably only useful when ctrl+c-ing during a fuzzy search

The idea is that this tool then becomes very nice to just pull an apk from the device (I especially love the fuzzy search) and open it in decompilers or other tools, which don't really need a properly signed version.

Let me know what you think :)