[dnssd-server] implement DNS-SD discovery proxy functionality in core

[abtink]

This commit implements a generic discovery proxy in the DNS-SD server. It uses a set of newly added otPlatDnssd platform DNS-SD(mDNS) APIs to start or stop browsers, SRV/TXT resolvers, and IPv6/IPv4 address resolvers. These APIs closely match the native OpenThread mDNS implementation.

OpenThread DNS-SD's existing QueryCallback mechanism, enabling customized discovery proxy implementations, remains supported.

This commit includes a comprehensive unit test. This test validates the discovery proxy's behavior, covering: standard use cases, request timeout, s hared resolver/browser usage for multiple queries with the same name, filtering of invalid addresses, and various edge cases.

[size-report[bot]]

Size Report of OpenThread

Merging #10050 into main(3873c6fcd5a8a9dd01b71e8efe32ef5dc7923bb1).

name	branch	text	data	bss	total
ot-cli-ftd	main	466528	856	66332	533716
	#10050	466528	856	66332	533716
	+/-	0	0	0	0
ot-ncp-ftd	main	435396	760	61544	497700
	#10050	435396	760	61544	497700
	+/-	0	0	0	0
libopenthread-ftd.a	main	235693	95	40278	276066
	#10050	235693	95	40278	276066
	+/-	0	0	0	0
libopenthread-cli-ftd.a	main	57589	0	8075	65664
	#10050	57589	0	8075	65664
	+/-	0	0	0	0
libopenthread-ncp-ftd.a	main	31863	0	5916	37779
	#10050	31863	0	5916	37779
	+/-	0	0	0	0
ot-cli-mtd	main	364528	760	51204	416492
	#10050	364528	760	51204	416492
	+/-	0	0	0	0
ot-ncp-mtd	main	347012	760	46432	394204
	#10050	347012	760	46432	394204
	+/-	0	0	0	0
libopenthread-mtd.a	main	157904	0	25166	183070
	#10050	157904	0	25166	183070
	+/-	0	0	0	0
libopenthread-cli-mtd.a	main	39812	0	8059	47871
	#10050	39812	0	8059	47871
	+/-	0	0	0	0
libopenthread-ncp-mtd.a	main	24743	0	5916	30659
	#10050	24743	0	5916	30659
	+/-	0	0	0	0
ot-cli-ftd-br	main	549872	864	131172	681908
	#10050	549888	864	131172	681924
	+/-	+16	0	0	+16
libopenthread-ftd-br.a	main	322994	100	105094	428188
	#10050	323587	100	105094	428781
	+/-	+593	0	0	+593
libopenthread-cli-ftd-br.a	main	71450	0	8099	79549
	#10050	71450	0	8099	79549
	+/-	0	0	0	0
ot-rcp	main	62280	564	20604	83448
	#10050	62280	564	20604	83448
	+/-	0	0	0	0
libopenthread-rcp.a	main	9542	0	5052	14594
	#10050	9542	0	5052	14594
	+/-	0	0	0	0
libopenthread-radio.a	main	19042	0	214	19256
	#10050	19042	0	214	19256
	+/-	0	0	0	0

[marius-preda]

Hi @abtink, the name of the commit has changed to "[mle] allow appending pending timestamp TLV with zero seconds" I guess it was by mistake and you just did a rebase of the branch.

On the other hand, is there anything else missing to merge this PR? It looks like it has all the approvals.

[abtink]

Hi @abtink, the name of the commit has changed to "[mle] allow appending pending timestamp TLV with zero seconds" I guess it was by mistake and you just did a rebase of the branch.

Thanks @marius-preda for noticing the commit message change. I am not sure how it happened. I just rebased it recently. It is interesting that it was changed to [mle] allow appending pending timestamp TLV with zero seconds (#10327) (which icnlude the (#10327) number which is auto-added by GitHub when a PR is merged. Seems like somehow git may have messed it up?

[marius-preda]

Hi @abtink, the name of the commit has changed to "[mle] allow appending pending timestamp TLV with zero seconds" I guess it was by mistake and you just did a rebase of the branch.

Thanks @marius-preda for noticing the commit message change. I am not sure how it happened. I just rebased it recently. It is interesting that it was changed to [mle] allow appending pending timestamp TLV with zero seconds (#10327) (which icnlude the (#10327) number which is auto-added by GitHub when a PR is merged. Seems like somehow git may have messed it up?

@abtink , indeed quite strange. Now it looks ok. Should we merge this PR then?