Feature: Reduce the bundle output size

[KrishnaPG]

Description

Currently, Sula + AntD + dependencies (lodash, moment, axios etc.) are coming up to 1.4MB bundle size in production mode. This is large and preferable to reduce it as much as possible.

Solution

• There seems to be individual UI components such as rc-menu (35KB), rc-select (34KB), rc-field-form (31KB) etc. that are being used in addition to AntD. Not sure if this duplication is required. It would be great if all these rc-* components could be replaced with just AntD components, since AntD is anyway being used for the rest. Also, just 35KB for menu (rc-menu), or 34KB for select (rc-select) etc. sounds lot of wasteful size.
• Not sure if axios (12.47Kb) is a required dependency for sula core functionality? Can it be made a peer-dependency (optional by the user)?
• moment (57.62KB) probably need to be replaced with day.js
• lodash (26.39KB) not sure how to reduce it - probably most of these used methods are already supported by ES6 natively? For example, assign, isArray etc. are natively supported by JS and utilizing them will reduce the additional dependency.

[KrishnaPG]

Also, using dynamic imports with React.lazy will reduce the initial load times: https://github.com/umijs/sula/issues/47