[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     

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[nand-nor]

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

[bukepo]

From the API doc, this should only be called when the device is attached. Could you add a check before issuing this call?

[nand-nor]

Added a check for this in 95dfb9b

[nand-nor]

/gemini review

[gemini-code-assist]

Code Review

This pull request adds support for taking over as the partition leader and setting the local leader weight via DBus. Specifically, it introduces the TakeoverLeader method and updates the LocalLeaderWeight property to be writable. The feedback suggests simplifying the TakeoverLeaderHandler implementation by removing a redundant role check, as otThreadBecomeLeader already performs this validation internally.

[gemini-code-assist]

The explicit role check in TakeoverLeaderHandler is redundant because otThreadBecomeLeader already performs this check internally and returns OT_ERROR_INVALID_STATE if the device is disabled or detached. We can simplify this handler by directly forwarding the result of otThreadBecomeLeader to ReplyOtResult, similar to other handlers like DetachHandler.

void DBusThreadObjectRcp::TakeoverLeaderHandler(DBusRequest &aRequest)
{
    auto threadHelper = mHost.GetThreadHelper();

    aRequest.ReplyOtResult(otThreadBecomeLeader(threadHelper->GetInstance()));
}