[core] Track bundle size changes on each PR

[oliviertassinari]

Summary 💡

This issue covers the last missing part of #37. It's also the logical next step after #18 where most of the suggested opportunities have been covered.

Examples 🌈

See mui/material-ui#33588 (comment).

Motivation 🔦

Bundle size matters, you can search for "bundle size" in https://mui.com/blog/2021-developer-survey-results/ and yet, we don't measure it. The purpose of this issue is to bring the bundle size change monitoring to MUI X (we might also need to fix it, see https://www.notion.so/mui-org/Opportunities-408a9771556a4715830d18f3749af753#3371fcfbefe940e7803c98e04118e9b4.

Order ID 💳 (optional)

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