feat(huawei): structured BGP route output (4/10)

[WilhelmZA]

Summary

Adds structured BGP route output for Huawei VRP, parsing display bgp routing-table detail (routes, AS-path, communities, RPKI/origin) into the standard structured table, and registers huawei as a structured-capable platform.

• New parser models/parsing/huawei.py + bgp_routestr_huawei output plugin; hardens the existing bgp_route_huawei input transform against non-list/invalid targets.
• Includes a parser unit test.
• The original Huawei parser work is by @CarlosSuporteISP (credited as commit co-author).

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Stacked series (4/10). Builds on pr/bgp-community-names.

Addresses

Adds structured Huawei BGP-route parsing and hardens the input transform (accepts a string or list target and tolerates non-prefix input). Intended to resolve the following upstream issues — confirmation on the affected hardware would be appreciated:

• Impossibile to use command "BGP Route" with Huawei NetEngine 8000 #315 — Impossible to use command "BGP Route" with Huawei NetEngine 8000
• Error in bgp_router query on Huawei #187 — Error in bgp_router query on Huawei