Add a new route for username availability check

Though this query is using the same jamid service as the contact query,
they should handle the responses from jamid service differently.

Change-Id: I42da3c5fc05ffe721a33288a2c7276eb52a9c624
diff --git a/client/src/utils/auth.ts b/client/src/utils/auth.ts
index 9adde32..7336639 100644
--- a/client/src/utils/auth.ts
+++ b/client/src/utils/auth.ts
@@ -40,7 +40,7 @@
 const idToStrengthValueCode: StrengthValueCode[] = ['too_weak', 'weak', 'medium', 'strong'];
 
 export function checkIfUserameIsRegistered(username: string) {
-  return axios.get(`/ns/username/${username}`, { baseURL: apiUrl });
+  return axios.get(`/ns/username/availability/${username}`, { baseURL: apiUrl });
 }
 
 export function checkPasswordStrength(password: string): PasswordCheckResult {