[rust-server] Add support for bearer token authentication

[mattdowdell]

As far as I can tell, the bulk of the work to support bearer tokens was already implemented to support OAuth, but never explicitly turned on. This was unexpectedly simple, so I susect I may have missed something.

Changes:

• Added bearer token to the security features for rust server.
• Supplemented the basic auth condition in the context template to handled basic auth and bearer token separately.
• Repurpose an exising sample to confirm the code generation works as expected.

The new sample builds without problems, so the only possibly issue is that the underlying swagger crate didn't implement this. However, there's already bearer support in the client and it's also used in the OAuth support in the server, so I don't see why it wouldn't work.

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CC @frol @farcaller @richardwhiuk @paladinzh

[richardwhiuk]

Nope looks good to me. I think we've just not had a requirement to support Bearers outside of OAuth before, so it's just not come up.

Thanks!

[richardwhiuk]

(Client support is already present -

openapi-generator/modules/openapi-generator/src/main/resources/rust-server/client-operation.mustache

Lines 324 to 335 in 4ea4ceb

	{{#isBasicBearer}}
	&AuthData::Bearer(ref bearer_header) => {
	let auth = swagger::auth::Header(bearer_header.clone());
	let header = match HeaderValue::from_str(&format!("{}", auth)) {
	Ok(h) => h,
	Err(e) => return Err(ApiError(format!("Unable to create Authorization header: {}", e)))
	};
	request.headers_mut().insert(
	hyper::header::AUTHORIZATION,
	header);
	},
	{{/isBasicBearer}}

)