[dbus] Add leader takeover and local leader weight API

[nand-nor]

Adds DBus APIs to takeover leader role and to set the local leader weight

[codecov]

Codecov Report

Attention: Patch coverage is 23.52941% with 13 lines in your changes missing coverage. Please review.

Project coverage is 45.37%. Comparing base (2b41187) to head (3022ab4).
Report is 725 commits behind head on main.

Files	Patch %	Lines
src/dbus/server/dbus_thread_object_rcp.cpp	23.52%	13 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2372       +/-   ##
===========================================
- Coverage   55.77%   45.37%   -10.41%     
===========================================
  Files          87       94        +7     
  Lines        6890     9931     +3041     
  Branches        0      749      +749     
===========================================
+ Hits         3843     4506      +663     
- Misses       3047     5206     +2159     
- Partials        0      219      +219     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[nand-nor]

This depends on if/when this OT PR merges openthread/openthread#9186