Implement websocket interaction between server and client

[rgallor]

Define shell.rs to handle the execution of shell commands.
Define device_server.rs to handle messages from clients.
Define sender_client.rs to send shell commands to the server and handle responses.
Define io_handler.rs to handle stdin/stdout operations.

Close #3

[codecov-commenter]

Codecov Report

Merging #8 (18ad124) into main (b505ae9) will not change coverage.
The diff coverage is 0.0%.

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Impacted Files	Coverage Δ
cli/src/main.rs	0.0% <0.0%> (ø)
rust-remote-shell/src/device_server.rs	0.0% <0.0%> (ø)
rust-remote-shell/src/io_handler.rs	0.0% <0.0%> (ø)
rust-remote-shell/src/sender_client.rs	0.0% <0.0%> (ø)
rust-remote-shell/src/shell.rs	0.0% <0.0%> (ø)

[harlem88]

Remove all certificates and keys from the repo, if they are useful for the project add a minimal guideline to generate them.