[libdatachannel] feat(libnice): added libnice feat

[crisboarna]

Describe the pull request Adding build feature to use libnice instead of libjuice

• What does your PR fix?

Adds extra feature nice which adds USE_NICE feature for building library to replace libjuice with libnice

• Which triplets are supported/not supported? Have you updated the CI baseline?

No

• Does your PR follow the maintainer guide?

Yes

• If you have added/updated a port: Have you run ./vcpkg x-add-version --all and committed the result?

Yes

[crisboarna]

All checks are passing now with requested changes @FrankXie05

[crisboarna]

@dan-shaw friendly reminder about this PR. :)

[Nemirtingas]

@crisboarna

Based on libdatachannel's documentation and @Nemirtingas opinion the nice feature does not comply with the maintainer guidelines to not introduce alternatives.

The existence of these properties in the rfcConfiguration struct suggests to me that it is not possible to change backends without affecting behavior, which makes this feature morally an alternative.

So our options for this PR are to either:

* leave the library as is, close this PR, and keep using overlays for `libnice` backend, or

* force using `libnice` instead of `libjuice` since that seems to be the more complete library (with the downside of depending on `glib`).

Since you're a user of this library I leave the final decision between those two up to you.

I had issues cross-compiling libdatachannel with libnice cause it requires glib and glib is quite big. I'd prefer not use libnice by default, if there was an alternative to either choose libnice or libjuice I'd prefer that solution.

[vicroms]

I had issues cross-compiling libdatachannel with libnice cause it requires glib and glib is quite big. I'd prefer not use libnice by default, if there was an alternative to either choose libnice or libjuice I'd prefer that solution.

Options in ports are a highly requested feature, but there is much design work that needs to be done before providing such a feature. I think is best to table this PR (and others similar to it) until such a feature is implemented.

[Nemirtingas]

I had issues cross-compiling libdatachannel with libnice cause it requires glib and glib is quite big. I'd prefer not use libnice by default, if there was an alternative to either choose libnice or libjuice I'd prefer that solution.

Options in ports are a highly requested feature, but there is much design work that needs to be done before providing such a feature. I think is best to table this PR (and others similar to it) until such a feature is implemented.

If you guys think that it would be better to use libnice by default, then go for it, I'm maintaining a fork of vcpkg to fix my cross-compilations issues anyway, I'll just change the libnice to libjuice library, thats it.