Create new interfaces for objects transmitted using the REST API

Changes:
- Create new IContact, IAccount, and IConversation interfaces in common/
    - These interfaces represent the serialized versions of the models which are transferred
    - The client models are classes which implement these interfaces
- Create new LookupResult interface for nameserver lookup results
- Create new IConversationMember interface for conversation members
    - The client interface ConversationMember extends this interface to have a Contact field rather than IContact
- Create new ConversationInfos interface for conversation infos
- Create new ContactDetails interface for contact details (used by contacts routes)
- Move request and response body interfaces into common/
- Merge AccountConfig into AccountDetails interface
- Create interfaces for server-only objects:
    - ConversationMemberInfos
    - ConversationRequestMetadata
- Ensure interfaces in jami-signal-interfaces.ts do not contain fields with JamiSwig types
- Rename models/ filenames to camelCase as they are not components
- Rewrite client models to have proper TypeScript accessors and remove unused getters
- Rewrite how client models are initialized from the serialized interface using .fromInterface static methods
- Make client models implement the interfaces in common/ for consistency
- Remove unneeded _next parameter for Express.js route handlers
- Use Partial<T> for all Express.js request body types on server
- Type all Axios response body types with interfaces

GitLab: #92
Change-Id: I4b2c75ac632ec5d9bf12a874a5ba04467c76fa6d
diff --git a/client/src/components/UsernameChooser.jsx b/client/src/components/UsernameChooser.jsx
index 19b8380..b098d1d 100644
--- a/client/src/components/UsernameChooser.jsx
+++ b/client/src/components/UsernameChooser.jsx
@@ -20,7 +20,7 @@
 import axios from 'axios';
 import { useEffect, useState } from 'react';
 
-import { apiUrl } from '../utils/constants.js';
+import { apiUrl } from '../utils/constants';
 
 const isInputValid = (input) => input && input.length > 2;