ISs #6 - Update endpoint, specs, tests, k8s routes to reflect API rules

One of the standards we have set is to use hyphens (-) instead of underscores (_) in URL path segments. This patch updates this API to follow this guideline.

spec/openapi.yaml

@@ -12,7 +12,7 @@ tags:
 -  name: Mailing Lists
    description: Definitions in relation to retrieval of mailing lists
 paths:
-   /mailing_lists:
+   /mailing-lists:
       get:
          tags:
          - Mailing Lists
@@ -27,7 +27,7 @@ paths:
                         $ref: '#/components/schemas/MailingLists'
             500:
                description: Error while retrieving data
-   /mailing_lists/available:
+   /mailing-lists/available:
       get:
          tags:
          - Mailing Lists
@@ -42,7 +42,7 @@ paths:
                         $ref: '#/components/schemas/MailingLists'
             500:
                description: Error while retrieving data
-   /mailing_lists/{listName}:
+   /mailing-lists/{listName}:
       parameters:
       -  name: listName
          in: path
@@ -64,7 +64,7 @@ paths:
                         $ref: '#/components/schemas/MailingList'
             500:
                description: Error while retrieving data
-   /mailing_lists/projects:
+   /mailing-lists/projects:
       get:
          tags:
          - Mailing Lists
@@ -79,7 +79,7 @@ paths:
                         $ref: '#/components/schemas/MailingListMapping'
             500:
                description: Error while retrieving data
-   /mailing_lists/projects/available:
+   /mailing-lists/projects/available:
       get:
          tags:
          - Mailing Lists
@@ -94,7 +94,7 @@ paths:
                         $ref: '#/components/schemas/MailingListMapping'
             500:
                description: Error while retrieving data
-   /mailing_lists/projects/{projectID}:
+   /mailing-lists/projects/{projectID}:
       parameters:
       -  name: projectID
          in: path