CLI: `dx new` should allow you to select multiple platforms

[nicoburns]

Feature Request

The dx new wizard for platform selection should be a multi-select rather than a single-select. This would put Dioxus's headline selling point of being multi-platform capable front and center in the user experience.

[ealmloff]

This looks like a duplicate of https://github.com/DioxusLabs/dioxus-template/issues/9. The dx new command is just a small shim over cargo generate which is driven by the dioxus-template repo

[DogeDark]

cargo-generate doesn't support multi-select at the moment. This was what I wanted for the 0.6 templates but due to cargo-generate's limitations, the primitive workaround was removed and now all platforms are useable as-is.