Remove hacked OSLO genconfig tool

This PS removes the pregenerated config templates producing using
the hacked oslo-genconfig tool. This results in both a much smaller
codebase and also more readable configuration by removing the
requirement to specify settings via oslo namespaced references.

This initial PS applies only to Keystone, A follow up will extend to
all remaining services.

Partially implements: blueprint remove-pregenerated-config-templates
See: https://blueprints.launchpad.net/openstack-helm/+spec/remove-pregenerated-config-templates

Change-Id: I3ced7ad02c703c767925a17b1a18f6158a878e83

doc/source/devref/index.rst

@@ -9,4 +9,5 @@ Contents:
    pod-disruption-budgets
    images
    endpoints
+   oslo-config
    upgrades

doc/source/devref/oslo-config.rst

@@ -0,0 +1,99 @@
+OSLO-Config Values
+------------------
+
+OpenStack-Helm generates oslo-config compatible formatted configuration files for
+services dynamically from values specified in a yaml tree. This allows operators to
+control any and all aspects of an OpenStack services configuration. An example
+snippet for an imaginary Keystone configuration is described here:
+
+::
+
+    conf:
+      keystone:
+        DEFAULT: # Keys at this level are used for section headings
+          max_token_size: 255
+        token:
+          provider: fernet
+        fernet_tokens:
+          key_repository: /etc/keystone/fernet-keys/
+        credential:
+          key_repository: /etc/keystone/credential-keys/
+        database:
+          max_retries: -1
+        cache:
+          enabled: true
+          backend: dogpile.cache.memcached
+        oslo_messaging_notifications:
+          driver: # An example of a multistring option's syntax
+            type: multistring
+            values:
+              - messagingv2
+              - log
+        security_compliance:
+          password_expires_ignore_user_ids:
+          # Values in a list will be converted to a comma seperated key
+            - "123"
+            - "456"
+
+This will be consumed by the templated ``configmap-etc.yaml`` manifest to
+produce the following config file:
+
+::
+
+    ---
+    # Source: keystone/templates/configmap-etc.yaml
+    apiVersion: v1
+    kind: ConfigMap
+    metadata:
+      name: keystone-etc
+    data:
+      keystone.conf: |+
+        [DEFAULT]
+        max_token_size = 255
+        transport_url = rabbit://keystone:password@rabbitmq.default.svc.cluster.local:5672/openstack
+        [cache]
+        backend = dogpile.cache.memcached
+        enabled = true
+        memcache_servers = memcached.default.svc.cluster.local:11211
+        [credential]
+        key_repository = /etc/keystone/credential-keys/
+        [database]
+        connection = mysql+pymysql://keystone:password@mariadb.default.svc.cluster.local:3306/keystone
+        max_retries = -1
+        [fernet_tokens]
+        key_repository = /etc/keystone/fernet-keys/
+        [oslo_messaging_notifications]
+        driver = messagingv2
+        driver = log
+        [security_compliance]
+        password_expires_ignore_user_ids = 123,456
+        [token]
+        provider = fernet
+
+Note that some additional values have been injected into the config file, this is
+performed via statements in the configmap template, which also calls the
+``helm-toolkit.utils.to_oslo_conf`` to convert the yaml to the required layout:
+
+::
+
+    {{- if empty .Values.conf.keystone.database.connection -}}
+    {{- tuple "oslo_db" "internal" "user" "mysql" . | include "helm-toolkit.endpoints.authenticated_endpoint_uri_lookup"| set .Values.conf.keystone.database "connection" | quote | trunc 0 -}}
+    {{- end -}}
+
+    {{- if empty .Values.conf.keystone.DEFAULT.transport_url -}}
+    {{- tuple "oslo_messaging" "internal" "user" "amqp" . | include "helm-toolkit.endpoints.authenticated_endpoint_uri_lookup" | set .Values.conf.keystone.DEFAULT "transport_url" | quote | trunc 0 -}}
+    {{- end -}}
+
+    {{- if empty .Values.conf.keystone.cache.memcache_servers -}}
+    {{- tuple "oslo_cache" "internal" "memcache" . | include "helm-toolkit.endpoints.host_and_port_endpoint_uri_lookup" | set .Values.conf.keystone.cache "memcache_servers" | quote | trunc 0 -}}
+    {{- end -}}
+
+    ---
+    apiVersion: v1
+    kind: ConfigMap
+    metadata:
+      name: keystone-etc
+    data:
+      keystone.conf: |+
+    {{ include "helm-toolkit.utils.to_oslo_conf" .Values.conf.keystone | indent 4 }}
+    {{- end }}