[react] Split src/system into its own package

[resir014]

Description

To allow for (hopefully) faster compile times, we should split off the system folder in @aksara-ui/react into its own package (@aksara-ui/system).

Implementation Model

This package will act as a wrapper for styled-system, adding helper APIs that have been present in aksara-ui, like the componentStyles API. Most of the styled-system general APIs (particularly the one that we use) will also be exported through this package.

Tasks

• Move types.ts file in theme folder into system folder, and provide these types as exportable.
• Create new package in monorepo called @aksara-ui/system, and move all files in the system folder there.
• Move styled-system + other dependencies as necessary into the new package.