Add K8s Gateway API resources

[franksc]

No description provided.

[markendr]

• any reason for making it "gateway.service" rather than "gateway.infrastructure" ..?
• best to use .Values.xx prefix on values settings to avoid ambiguous scope
• add a "gateway.existingGatewayRefs" option or similar to allow gateway sharing among apps, don't provision gateway resource if provided, just set httproute gateway refs using provided refs
• also need allowedRoutes.namespaces.from: All for shared gateway (ie in another namespace)
• we currently provision http-to-https redirect listener with the hostname, i don't think it will work without hostname if there are multiple tls listeners with multiple hostnames

[markendr]

we also had to add httproute timeouts to allow large file downloads. could this be allowed with optional values ..?

--- a/apps/ais-xnat/httproute.yaml
+++ b/apps/ais-xnat/httproute.yaml
@@ -31,6 +31,9 @@ spec:
         - path:
             type: PathPrefix
             value: /
+      timeouts:
+        request: 10m
+        backendRequest: 10m
       backendRefs:

[franksc]

I have implemented the above suggestions with this batch of commits.

Using an existing Gateway resource not managed by this chart should be accommodated with something like:

gateway:
  enabled: true
  createGateway: false
  gatewayName: [name of existing Gateway]
  gatewayNamespace: [namespace of existing Gateway]
  http:
    hosts:
      - host: xnat.example.com
        listenerName: [name of listener in existing Gateway]

TBD: probably split HTTPRoute stuff into a separate template file, flatten some repeated nested references