Solve the bugs for SONiC CLI Auto-generation

[oplklum]

Solve the bugs for SONiC CLI Auto-generation referenced in #3221

1. Fixed the error description for config update
2. Not displaying the command of not configurable table that defined config false in the yang model.
3. Support showing other db table data defined in sonic yang model, not just config db.

What I did

1. Fixed the error description for config update
2. Support config and db-name query in yang_parser.py
3. Change config.py.j2 to filter config false table
4. Extend show.py.j2 to support query of non confg db.
5. Compatible with previous programs and tests.

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)

[linux-foundation-easycla]

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• ✅ login: oplklum / name: MaoLu (8dd25a9)