tor-netdoc: Remove redundant `IntroPointDesc` struct.
This commit replaces tor_netdoc::hsdesc::inner::IntroPointDesc
with
the (almost identical) tor_netdoc::hsdesc::IntroPointDesc
.
The only difference between the two structs is that
inner::IntroPointDesc
wraps a Vec<LinkSpec>
instead of a
Vec<EncodedLinkSpec>
. Since EncodedLinkSpec
can be derived from
LinkSpec
(and vice-versa), and since hsdesc::inner::IntroPointDesc
never made it in our public API, this commit also removes
hsdesc::inner::IntroPointDesc
in favour of hsdesc::IntroPointDesc
.