feat: migrate snapshot files too [LIBS-681]

[KaiVandivier]

LIBS-681

Tested out in the Dashboard app, and the snapshots are indeed use for comparison -- the platform changes seem to have removed white space in some snaps as seen in the second screenshot below, for example.

One potential shortcoming of the script I noticed, however, is that it doesn't update file paths for things like mocked jest modules, resulting in errors like:

 FAIL  src/components/Item/VisualizationItem/__tests__/Item.spec.jsx
  ● Test suite failed to run

    Cannot find module '../../ItemHeader/DeleteItemButton.js' from 'src/components/Item/VisualizationItem/__tests__/Item.spec.jsx'

Screenshots

[dhis2-bot]

:tada: This PR is included in version 12.0.0-alpha.16 :tada:

The release is available on:

• npm package (@alpha dist-tag)
• npm package (@alpha dist-tag)
• npm package (@alpha dist-tag)
• npm package (@alpha dist-tag)
• GitHub release

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