feature: avoid rerenders

[devrnt]

Using useState in IntercomProvider causes unnecessary rerenders. This is avoided by making use of useRef.

• Drop the isBooted dependency in the useCallbacks's.
  As of now the IntercomProvider causes no rerenders on boot, update and so on...

[github-actions]

Size Change: -23 B (0%)

Total Size: 9.25 kB

Filename	Size	Change
dist/react-use-intercom.cjs.development.js	3.46 kB	-12 B (0%)
dist/react-use-intercom.cjs.production.min.js	2.23 kB	+1 B
dist/react-use-intercom.esm.js	3.42 kB	-12 B (0%)

ℹ️ View Unchanged

Filename	Size	Change
dist/index.js	152 B	0 B

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