New frontend web client written using Rust and Yew.rs (#459)

Adds a new web client runner built from the ground up using rust and
yew.rs.
Part of #261 

Right now web client must be manually built and launched separate to
launching the backend. A followup PR will add a new flag to tell runner
to use the new web client. Both the old and new client will be supported
until the new front end has been thoroughly tested and has feature
parity.

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Co-authored-by: Julien Cretin <github@ia0.eu>

crates/runner-host/crates/web-client/.gitignore

@@ -0,0 +1 @@
+/dist/