devel/hub: update 2.7.0 to 2.9.0

• Shell Completion Files are installed by default;
• remove *_RUN_DEPENDS from the shell completion options;
• new option to chose backend to be used (D19117).

PR: 235598
Submitted by: swills
Approved by: rene (mentor)
Differential Revision: https://reviews.freebsd.org/D19028