[WIP] Add a Homepage URL entry for vcpkg ports

[pravic]

Fixes #1642.

When browsing new ports, it is often hard to understand their purpose. Or where they come from (without looking into portfile.cmake). Some examples: http-parser, ode, and lots of others.

The idea was to add a human readable URL in port's description, thus vcpkg could print it in vcpkg list and vcpkg search results. However I am not sure about the best place for URL at the moment, so it is an open question.

This PR does not implement corresponding changes in vcpkg source (to support the new field), it just adds a Homepage entry to almost all ports (except empty ones like winsock2 or atlmfc and except modularized subports like qt5- or boost-). URLs are extracted from vcpkg_from_github, vcpkg_from_bitbucket, vcpkg_download_distfile so they can be not perfect, but it is the best I can do :)

Unresolved questions:

0. The name of the homepage entry in CONTROL files. Homepage? URL? Repository? Actually, most of repositories use multiple entries (homepage and repository in Rust crates, homepage, download and issue tracker URLs in pypi and so on).
1. Do we need to print URLs or we can leave them in CONTROL files just for manual reading? Personally, I would go without print.
2. If we are going to print, when and where? Descriptions often quite big and do not fit in one line in console.
3. May be introduce an additional command similar to cargo-show (pip show, npm view, etc.) which will print all information about particular port?

[jasjuang]

This is a great idea

[soul4soul]

0. I vote for Homepage. It should be a URL to the webpage which is the primary entry point into learning about the port. For software which has a dedicated website it would be a URL to that website. Other software with no dedicated website would be a URL to the github repo.
1. See 3.
2. See 3.
3. I vote for having a show command which would print all of the information about a particular port.

Why would not include HomePage for each subport too?

[luzpaz]

This would be very useful. Is there an ETA on when this will be merged ?

[Rastaban]

/azp run

[Rastaban]

The only failure is shogun:x64-linux and looks like it is unrelated to this PR. It should probably not hold up this PR.

Update: on rerun the port passed, it is probably just a flaky port.

[MVoz]

@Rastaban add in templates ?
vcpkg\scripts\templates\CONTROL.in

Source: @PORT@
Version: 
#Homepage: 
Description: 
#Build-Depends: