UCT/PLUGIN: add definition in uct_iface_attr_v2_t for uct_iface_query_v2 (#11316)

* UCT/PLUGIN: add definition in uct_iface_attr_v2_t for uct_iface_query_v2

* UCT/PLUGIN: add definition in uct_iface_attr_v2_t for uct_iface_query_v2

* UCT/PLUGIN: modifications based on comments

* UCT/PLUGIN: modifications for clang-format

* UCT/PLUGIN: update comment for flags in uct_iface_attr_v2_t

* UCT/PLUGIN: update comment for uct_iface_attr_field

* UCT/PLUGIN: remove leftover conflict marker

* UCT/PLUGIN: format update

* UCT/PLUGIN: remove duplicate flag definition

* UCT/PLUGIN: set token_length to 0 in uct_iface_base_query_v2

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Co-authored-by: Leonid Genkin <lgenkin@nvidia.com>