[mle] update `otThreadBecomeLeader()` to allow leader take over

[abtink]

This commit updates the otThreadBecomeLeader() API (and its related core MleRouter::BecomeLeader() method) to allow an already attached device to take over as leader, creating a new partition. For this to work, the local leader weight (otThreadGetLocalLeaderWeight()) must be greater than the weight of the current leader (which can be retrieved using otThreadGetLeaderWeight()). If it is not, error code OT_ERROR_NOT_CAPABLE is returned to indicate to the caller that they need to adjust the local weight.

This commit also updates the related CLI command and adds a new test, test-022-leader-take-over.py, to validate the newly added mechanism.

---

Related to SPEC-1140.

[size-report[bot]]

Size Report of OpenThread

Merging #9186 into main(aba7aede1476339abe3032a250349d67a4ec1605).

name	branch	text	data	bss	total
ot-cli-ftd	main	466816	856	66364	534036
	#9186	466848	856	66364	534068
	+/-	+32	0	0	+32
ot-ncp-ftd	main	435908	760	61592	498260
	#9186	435940	760	61592	498292
	+/-	+32	0	0	+32
libopenthread-ftd.a	main	236112	95	40302	276509
	#9186	236142	95	40302	276539
	+/-	+30	0	0	+30
libopenthread-cli-ftd.a	main	57580	0	8075	65655
	#9186	57580	0	8075	65655
	+/-	0	0	0	0
libopenthread-ncp-ftd.a	main	32127	0	5924	38051
	#9186	32127	0	5924	38051
	+/-	0	0	0	0
ot-cli-mtd	main	365472	760	51236	417468
	#9186	365472	760	51236	417468
	+/-	0	0	0	0
ot-ncp-mtd	main	348188	760	46480	395428
	#9186	348188	760	46480	395428
	+/-	0	0	0	0
libopenthread-mtd.a	main	158941	0	25190	184131
	#9186	158941	0	25190	184131
	+/-	0	0	0	0
libopenthread-cli-mtd.a	main	39795	0	8059	47854
	#9186	39795	0	8059	47854
	+/-	0	0	0	0
libopenthread-ncp-mtd.a	main	25007	0	5924	30931
	#9186	25007	0	5924	30931
	+/-	0	0	0	0
ot-cli-ftd-br	main	551576	864	131228	683668
	#9186	551608	864	131228	683700
	+/-	+32	0	0	+32
libopenthread-ftd-br.a	main	325027	100	105142	430269
	#9186	325057	100	105142	430299
	+/-	+30	0	0	+30
libopenthread-cli-ftd-br.a	main	71711	0	8099	79810
	#9186	71711	0	8099	79810
	+/-	0	0	0	0
ot-rcp	main	62312	564	20636	83512
	#9186	62312	564	20636	83512
	+/-	0	0	0	0
libopenthread-rcp.a	main	9734	0	5060	14794
	#9186	9734	0	5060	14794
	+/-	0	0	0	0
libopenthread-radio.a	main	18991	0	222	19213
	#9186	18991	0	222	19213
	+/-	0	0	0	0

[codecov[bot]]

Codecov Report

Merging #9186 (6fa1f69) into main (70adcab) will increase coverage by 0.00%. The diff coverage is 83.33%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #9186   +/-   ##
=======================================
  Coverage   85.89%   85.89%           
=======================================
  Files         551      551           
  Lines       73268    73271    +3     
=======================================
+ Hits        62932    62938    +6     
+ Misses      10336    10333    -3     

Files Changed	Coverage Δ
src/core/thread/mle_router.hpp	84.84% <ø> (ø)
src/core/thread/mle_router.cpp	84.01% <75.00%> (-0.03%)	:arrow_down:
src/core/api/thread_ftd_api.cpp	76.96% <100.00%> (ø)
src/core/thread/mle.cpp	88.99% <100.00%> (-0.09%)	:arrow_down:

... and 19 files with indirect coverage changes

[nand-nor]

@abtink @EskoDijk any plans to merge this in?

[abtink]

@abtink @EskoDijk any plans to merge this in?

I am okay merging this. Just rebased it on main.

[jwhui]

@abtink @EskoDijk any plans to merge this in?

@nand-nor , merged!