Dependencies:
- Upgrade MUI and  MUI Icons peer dependencies to ^7
- Upgrade MUI and MUI Icons dev dependencies to ^7.3
- Increase MUI x-date-pickers peer dependency to ^7.28 to be compatible with MUI 7
- Regenerate pnpm lockfile

Code adaptions:
- Migrate from the old Grid (now GridLegacy) to Grid2 (now Grid) according to MUI's migration guide
- Import all icons from @mui/icons-material to get rid of rollup warnings
- In MuiCheckbox and MuiToggle: Migrate from deprecated `inputProps` to `slotProps.input`.
- Adapt Material Array Layout tests to internal changes of MUI icon buttons

Dev:
- Fix/Adapt Material dev application webpack config

Example app:
- Removed obsolete custom cjs compatibility plugin from react material example app build.
  It was necessary for previous MUI versions that were based on CJS instead of ESM