NTPsec 1.2.x with Pool Extensions and SRV client support

This is based on commit 32a950f of the NTPsec project, and incorporates:

• Some changes made by upstream that help as a client to use the NTS pool (correctly setting the SNI field, allowing the pool directive to be used with nts sources)

• Support for srv based NTS time sources, so NTPsec can be used as a client for a SRV-based pool.

• The pool extensions based on https://datatracker.ietf.org/doc/draft-ietf-ntp-nts-keyexchange-pool/00/ (with the codepoint as pre-allocated by IANA), to participate as a server in the KELB-based pool. That means that this version is not compatible with the earlier experimental KELB pool.

NTPsec 1.2.x with Pool Extensions and SRV client support

This is based on commit 32a950f of the NTPsec project, and incorporates:

• Some changes made by upstream that help as a client to use the NTS pool (correctly setting the SNI field, allowing the pool directive to be used with nts sources)

• Support for srv based NTS time sources, so NTPsec can be used as a client for a SRV-based pool.

• The pool extensions based on https://datatracker.ietf.org/doc/draft-venhoek-nts-pool/04/ (with some typos corrected), to participate as a server in the KELB-based pool.

NTPsec 1.2.4 with Pool Extensions revision 1

This replays the patches necessary for adding NTS Pool Extensions on top of 1.2.4

This is in line with https://datatracker.ietf.org/doc/draft-venhoek-nts-pool/04/ (with some typos corrected)