PVST Feaute CLI support

[bendrapubalareddy]

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Changes: modified: clear/main.py new file: clear/stp.py modified: config/main.py new file: config/stp.py modified: config/vlan.py modified: debug/main.py new file: debug/stp.py modified: scripts/fast-reboot modified: scripts/generate_dump modified: show/main.py new file: show/stp.py modified: sonic_installer/main.py modified: tests/mock_tables/appl_db.json modified: tests/mock_tables/config_db.json modified: tests/mock_tables/state_db.json new file: tests/stp_test.py

What I did

How I did it

How to verify it

Previous command output (if the output of a command-line utility has changed)

New command output (if the output of a command-line utility has changed)