[Mellanox][202012] Enhance Python3 support for platform API (back-porting #7410)

[stephenxs]

• Why I did it
  This is to back-port Azure 7410 to 202012 branch.
  Enhance the Python3 support for platform API. Originally, some platform APIs call SDK API which didn't support Python 3. Now the Python 3 APIs have been supported in SDK 4.4.3XXX, Python3 is completely supported by platform API

• How I did it
  Start all platform daemons from python3

1. Remove #/usr/bin/env python at the beginning of each platform API file as the platform API won't be started as daemons but be imported from other daemons.
2. Adjust SDK API calls accordingly

• How to verify it
  Manually test and run regression platform test

Signed-off-by: Stephen Sun stephens@nvidia.com

Why I did it

How I did it

How to verify it

Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006
• 202012

Description for the changelog

A picture of a cute animal (not mandatory but encouraged)

[stephenxs]

Looks like ci issue. @qiluo-msft can you help on this? thanks

2021-06-18T00:55:04.4616635Z ##[section]Starting: Clean Workspace
2021-06-18T00:55:04.4824272Z ==============================================================================
2021-06-18T00:55:04.4824824Z Task         : Command line
2021-06-18T00:55:04.4825228Z Description  : Run a command line script using Bash on Linux and macOS and cmd.exe on Windows
2021-06-18T00:55:04.4825478Z Version      : 2.182.0
2021-06-18T00:55:04.4825811Z Author       : Microsoft Corporation
2021-06-18T00:55:04.4826210Z Help         : https://docs.microsoft.com/azure/devops/pipelines/tasks/utility/command-line
2021-06-18T00:55:04.4826508Z ==============================================================================
2021-06-18T00:55:04.6541703Z Generating script.
2021-06-18T00:55:04.6549574Z ========================== Starting Command Output ===========================
2021-06-18T00:55:04.6568326Z [command]/usr/bin/bash --noprofile --norc /agent/_work/_temp/c5a60545-e987-42eb-bce0-0cddc5a32b96.sh
2021-06-18T00:55:04.6697053Z sudo: a terminal is required to read the password; either use the -S option to read from standard input or configure an askpass helper
2021-06-18T00:55:04.6763126Z sudo: a terminal is required to read the password; either use the -S option to read from standard input or configure an askpass helper
2021-06-18T00:55:04.7073009Z sudo: a terminal is required to read the password; either use the -S option to read from standard input or configure an askpass helper
2021-06-18T00:55:04.7177002Z sudo: a terminal is required to read the password; either use the -S option to read from standard input or configure an askpass helper
2021-06-18T00:55:04.7267960Z sudo: a terminal is required to read the password; either use the -S option to read from standard input or configure an askpass helper
2021-06-18T00:55:04.7345524Z ##[error]Bash exited with code '1'.
2021-06-18T00:55:04.7394630Z ##[section]Finishing: Clean Workspace

[liat-grozovik]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).