Add ability to automatically pick up the latest apktool.jar version

[codebymikey]

Similar to the work done on #2120, adding the ability to automatically pick up the latest apktool version for the user.

If the script finds an apktool.jar it's selected automatically, otherwise it looks for jar versions available in its directory with the name format apktool_<version>.jar and picks the latest accordingly.

[iBotPeaches]

Is this a pattern someone started somewhere in some tool/guide that caused a lot of people to collect the versions in this manner?

[codebymikey]

No, I think it's mainly because that's the default naming convention of the jar files downloaded from the GitHub releases, so it's a lot more convenient saving them directly within the same directory as the wrapper and having it work that way without needing to rename it.