Summary: Android apps can use multiple processes (eg, chrome), which are identified as <package_name>:<process_name> in logs. The names are defined in the manifest.
The main process is referred to as simply <package_name> by android.
Add the ability to specify a target process as part of what was until now the package name in pidcat, or all processes if no process is specified.
Usage:
* pidcat <package_name> will match all of an app's processes (catchall).
* pidcat <package_name>:<process_name> will match a given named process.
** In particular, pidcat <package_name>: will ensure only the app's main/default process is matched.
Test Plan: Run the script, try out with no process, empty (aka default) process, named process. Try multiple entries.
