Allow to set a `CMAKE_CUDA_STANDARD` different from `CMAKE_CXX_STANDARD`

[aurianer]

Fixes #699

• [x] Add a CI config using a different CXX and CUDA standard
• [x] Add a GPU stdexec config with different CXX and CUDA standards

Note: Looks like there are problems with fmt@10, will look into it in a separate PR.

[aurianer]

bors try

[bors[bot]]

try

Build failed:

• ci/circleci: arm64_build

[aurianer]

bors try

[bors[bot]]

try

Build failed:

• jenkins/cscs-daint/gcc-cuda-11-debug

[aurianer]

bors try

[bors[bot]]

try

Build failed:

• github/macos/debug

[aurianer]

bors try

[bors[bot]]

try

Build failed:

• ci/circleci: cmake_format

[aurianer]

bors try

[bors[bot]]

try

Build failed:

• ci/circleci: arm64_build

[aurianer]

Looks good now :)

[sonarqubecloud[bot]]

SonarCloud Quality Gate failed.   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
16 Code Smells

No Coverage information
0.0% Duplication

Catch issues before they fail your Quality Gate with our IDE extension SonarLint