Add package to allow noarch python packages to depend on cupy

recipes/cupyifcudaavailable/LICENSE

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+Copyright (c) 2024, conda-forge
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright notice,
+  this list of conditions and the following disclaimer in the documentation
+  and/or other materials provided with the distribution.
+
+* Neither the name of staged-recipes nor the names of its
+  contributors may be used to endorse or promote products derived from
+  this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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recipes/cupyifcudaavailable/conda_build_config.yaml

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+with_cuda:
+  - true
+  - false

recipes/cupyifcudaavailable/meta.yaml

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+package:
+  name: cupyifcudaavailable
+  version: "1.0.0"
+
+build:
+  # Tell the solver to strongly prefer the cuda installation
+  number: 0            # [not with_cuda]
+  number: 300          # [    with_cuda]
+  noarch: generic
+  string: cuda_{{ PKG_BUILDNUM }}  # [with_cuda]
+  string: cpu_{{ PKG_BUILDNUM }}   # [not with_cuda]
+
+requirements:    # [with_cuda]
+  run:           # [with_cuda]
+    - __cuda     # [with_cuda]
+    - cupy       # [wtih_cuda]
+
+# CIs don't really have cuda, and thus  would fail at resolving __cuda
+test:                                      # [not with_cuda]
+  commands:                                # [not with_cuda]
+    - echo "no tests for this package"     # [not with_cuda]
+
+about:
+  home: https://github.com/conda-forge/cupyifcudaavailable-feedstock
+  license: BSD-3-Clause
+  license_file: LICENSE
+  summary: 'Allows noarch packages to depend on cupy without large downloads'
+
+extra:
+  recipe-maintainers:
+    - hmaarrfk