Add shell-completions for dx

[sermuns]

I followed the simple example from https://github.com/clap-rs/clap/blob/master/clap_complete/examples/completion-derive.rs.

Problem is, the main command seems to be too big, causing a runtime stack overflow when trying to generate completions...

$ cargo run -- completions bash
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.62s
     Running `/home/sermuns/.cache/cargo/debug/dx completions bash`

thread 'main' (2234839) has overflowed its stack
fatal runtime error: stack overflow, aborting

$ cargo run --release -- completions bash
   Compiling dioxus-cli v0.7.3 (/home/sermuns/Git/dioxus/packages/cli)
    Finished `release` profile [optimized] target(s) in 9.92s
     Running `/home/sermuns/.cache/cargo/release/dx completions bash`

thread 'main' (2234993) has overflowed its stack
fatal runtime error: stack overflow, aborting

Fixes #5061 (once I have figured out a solution for the stack overflow...)

[ealmloff]

That may be caused by the @server and @client subcommands which use ChainedCommand to match recursively

[sermuns]

Sounds like a reasonable culprit, let me investigate.