[alpaka] Add new port

[bernhardmgruber]

This PR adds a new port called alpaka, which adds the alpaka header-only library.
There is already an equally named package on spack.

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

Alpaka supports Windows, Linux and MacOS. It should work on all triplets.

• Does your PR follow the maintainer guide?

I tried.

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

Yes

[github-actions]

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PRs must add only one version and must not modify any published versions

When making any changes to a library, the version or port-version in vcpkg.json or CONTROL must be modified.

error: checked-in files for alpaka have changed but the version was not updated
version: 0.9.0
old SHA: 3ffad67273f1e214a7bfbc407a5cacde236e1c82
new SHA: 8afc1b74dc92c51ef944368ce80e4a7d77672cec
Did you remember to update the version or port version?
Use --overwrite-version to bypass this check
***No files were updated***

[JonLiu1993]

@bernhardmgruber , Thanks for your pr, when I tested the alpakax64-windows usage, I got a error:
could you please take a look:

Rebuild started...
1>------ Rebuild All started: Project: ZERO_CHECK, Configuration: Debug x64 ------
1>Checking Build System
2>------ Rebuild All started: Project: main, Configuration: Debug x64 ------
2>Building Custom Rule C:/Users/test/source/repos/CMakeProject42/CMakeProject42/CMakeLists.txt
2>CMakeProject42.cpp
2>LINK : fatal error LNK1104: cannot open file '<name>.lib'
2>Done building project "main.vcxproj" -- FAILED.
3>------ Skipped Rebuild All: Project: ALL_BUILD, Configuration: Debug x64 ------
3>Project not selected to build for this solution configuration 
========== Rebuild All: 1 succeeded, 1 failed, 1 skipped ==========

CMakelists.txt:

cmake_minimum_required (VERSION 3.8)

project(test)

find_package(alpaka CONFIG REQUIRED)

add_executable (main "CMakeProject42.cpp" "CMakeProject42.h")

target_link_libraries(main PRIVATE <name> alpaka alpaka::alpaka)

CMakeProject42.cpp

// CMakeProject42.cpp : Defines the entry point for the application.
//

#include "CMakeProject42.h"
#include "alpaka/alpaka.hpp"

using namespace std;

int main()
{
	cout << "Hello CMake." << endl;
	return 0;
}

[bernhardmgruber]

@JonLiu1993, please remove the library <name> from target_link_libraries: and just link against alpaka:

target_link_libraries(main PRIVATE alpaka::alpaka)

Then your example builds locally on my machine. Mind though, that alpaka requires at least CMake 3.18 and if you want to use the CUDA backend, you must use alpaka_add_executable instead of add_executable, because we need to change the source language from CXX to CUDA for all source files.

[JonLiu1993]

@bernhardmgruber, I remove from target_link_libraries and test usage successfully

[dg0yt]

target_link_libraries(main PRIVATE <name> alpaka alpaka::alpaka)

If this was the usage proposal from vcpkg tool, then the new port needs a usage file, or it will be recorded in #20190.

[bernhardmgruber]

target_link_libraries(main PRIVATE <name> alpaka alpaka::alpaka)

If this was the usage proposal from vcpkg tool, then the new port needs a usage file, or it will be recorded in #20190.

I just checked, this is how the usage is reported:

alpaka provides CMake targets:

    # this is heuristically generated, and may not be correct
    find_package(alpaka CONFIG REQUIRED)
    target_link_libraries(main PRIVATE <name> alpaka alpaka::alpaka)

I added a usage file now. In this process, I also squashed the commits.