segfetcher: Add functionality to delete NextQuery entries

[lukedirtwalker]

This makes it possible to easily refetch segments for revoked links.
Also for sciond we need to delete next query entries for the refresh flag.

Contributes #2454

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This change is 

[oncilla]

Reviewable status: 0 of 2 files reviewed, 1 unresolved discussion (waiting on @lukedirtwalker and @oncilla)

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go/lib/infra/modules/segfetcher/revocation.go, line 63 at r1 (raw file):

		switch r.Type {
		case proto.PathSegType_up:
			req = Request{Src: r.Seg.LastIA(), Dst: addr.IA{I: r.Seg.FirstIA().I}}

Does this not potentially delete to many entries?

[lukedirtwalker]

Reviewable status: 0 of 2 files reviewed, 1 unresolved discussion (waiting on @oncilla)

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go/lib/infra/modules/segfetcher/revocation.go, line 63 at r1 (raw file):

Previously, Oncilla wrote…

Does this not potentially delete to many entries?

How do you mean? We always store LocalIA -> LocalISD-0 for NextQuery entries for up segments. Fetching up segments at the local PS shouldn't be too much of a problem since it is always local.

[oncilla]

Reviewed 2 of 2 files at r1.
Reviewable status: complete! all files reviewed, all discussions resolved

[oncilla]

Reviewed 2 of 2 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved

[oncilla]

Reviewable status: complete! all files reviewed, all discussions resolved