**- Why I did it**
python2 is end of life and SONiC is going to support python3. This PR is going to support:
1. Build pmon daemons with python3
2. Install and run python3 version pmon daemons
**- How I did it**
1. Change pmon daemons make files to build bothe python2 and python3 whl
2. Change docker-platform-monitor make files to install both python2 and python3 whl
3. Change pmon docker startup files to start pmon daemons according to the supported platform API version
As part of migrating all Python-based package installers to wheel format rather than Debian packages. Also to allow for easily building a Python 3 version of the package in the near future.
- Also remove some references to sonic-daemon-base which I previously missed and add missing sonic-py-common dependency for sonic-pcied.
As part of consolidating all common Python-based functionality into the new sonic-py-common package, this pull request:
1. Redirects all Python applications/scripts in sonic-buildimage repo which previously imported sonic_device_util or sonic_daemon_base to instead import sonic-py-common, which was added in https://github.com/Azure/sonic-buildimage/pull/5003
2. Replaces all calls to `sonic_device_util.get_platform_info()` to instead call `sonic_py_common.get_platform()` and removes any calls to `sonic_device_util.get_machine_info()` which are no longer necessary (i.e., those which were only used to pass the results to `sonic_device_util.get_platform_info()`.
3. Removes unused imports to the now-deprecated sonic-daemon-base package and sonic_device_util.py module
This is the next step toward resolving https://github.com/Azure/sonic-buildimage/issues/4999
Also reverted my previous change in which device_info.get_platform() would first try obtaining the platform ID string from Config DB and fall back to gathering it from machine.conf upon failure because this function is called by sonic-cfggen before the data is in the DB, in which case, the db_connect() call will hang indefinitely, which was not the behavior I expected. As of now, the function will always reference machine.conf.
