[wasm] Check if `python` is installed when installing the workload

[lewing]

Right now the build expects python to be in the path on linux but ends up checking this by running emcc --version and not surfacing the error text.

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Issue Details

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Right now the build expects python to be in the path on linux but ends up checking this by running emcc --version and not surfacing the error text.

Author:	lewing
Assignees:	radical
Labels:	arch-wasm, area-Build-mono
Milestone:	6.0.0

[lewing]

Likely the cause of #54342

[radical]

1. [wasm] Build improvements #61276 surfaces the output of emcc --version correctly, so the error would show up for the user
2. But we should also check for python when installing the workload