Fix imports of ‘core’ from full page examples

[36degrees]

After the changes in #4955 we need to follow the instructions in our own deprecation message to update the imports from our full-page examples:

Importing using govuk/core/all is deprecated. Update your import statement to import govuk/core/index.

[github-actions[bot]]

:clipboard: Stats

File sizes

File	Size
dist/govuk-frontend-development.min.css	113.32 KiB
dist/govuk-frontend-development.min.js	42.21 KiB
packages/govuk-frontend/dist/govuk/all.bundle.js	87.21 KiB
packages/govuk-frontend/dist/govuk/all.bundle.mjs	81.95 KiB
packages/govuk-frontend/dist/govuk/all.mjs	4.17 KiB
packages/govuk-frontend/dist/govuk/govuk-frontend-component.mjs	359 B
packages/govuk-frontend/dist/govuk/govuk-frontend.min.css	113.3 KiB
packages/govuk-frontend/dist/govuk/govuk-frontend.min.js	42.2 KiB
packages/govuk-frontend/dist/govuk/i18n.mjs	5.55 KiB

Modules

File	Size (bundled)	Size (minified)
all.mjs	77.67 KiB	40.19 KiB
accordion.mjs	22.71 KiB	12.85 KiB
button.mjs	5.98 KiB	2.69 KiB
character-count.mjs	22.4 KiB	9.92 KiB
checkboxes.mjs	5.83 KiB	2.83 KiB
error-summary.mjs	7.89 KiB	3.46 KiB
exit-this-page.mjs	17.1 KiB	9.26 KiB
header.mjs	4.46 KiB	2.6 KiB
notification-banner.mjs	6.26 KiB	2.62 KiB
password-input.mjs	15.15 KiB	7.25 KiB
radios.mjs	4.83 KiB	2.38 KiB
skip-link.mjs	4.39 KiB	2.18 KiB
tabs.mjs	10.13 KiB	6.11 KiB

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Action run for f991f01372e2330d2a2d9e0c7d0cba19f05a373d