[YANG] Update device_metadata to add suppress-fib-pending field

[Gfrom2016]

Why I did it

BGP pending FIB suppression is introduced in #12853, hence updating the YANG model.

Work item tracking

• Microsoft ADO (number only): 28398135

How I did it

Added a new field 'suppress-fib-pending' in the DEVICE_METADATA YANG model table.
Added UT for YANG model changes.

How to verify it

Run PR tests.
Apply empty.json file to verify:

admin@str2-7050cx3-acs-02:~$ sudo config apply-patch empty.json 
Patch Applier: Patch application starting.
Patch Applier: Patch: []
Patch Applier: Getting current config db.
Patch Applier: Simulating the target full config after applying the patch.
Patch Applier: Validating all JsonPatch operations are permitted on the specified fields
Patch Applier: Validating target config does not have empty tables, since they do not show up in ConfigDb.
Patch Applier: Sorting patch updates.
Patch Applier: The patch was converted into 0 changes.
Patch Applier: Applying 0 changes in order.
Patch Applier: Verifying patch updates are reflected on ConfigDB.
Patch Applier: Patch application completed.
Patch applied successfully.
admin@str2-7050cx3-acs-02:~$ 

Signed-off-by: zitingguo-ms zitingguo@microsoft.com

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

• 201811
• 201911
• 202006
• 202012
• 202106
• 202111
• 202205
• 202211
• 202305

Tested branch (Please provide the tested image version)

Description for the changelog

Link to config_db schema for YANG module changes

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

[lolyu]

LGTM

[yutongzhang-microsoft]

LGTM

[Gfrom2016]

@wen587 Could you help to review this?

[StormLiangMS]

LGTM