Update silenced warnings for Sass compiler

[romaricpascal]

Missed a couple of places we were silencing Sass dependencies when I updated #5442, which this PR fixes (adding the ignoring of import and `global-builtin').

In addition, it also centralise the configuration related to deprecations in the @govuk-frontend/config module. While this scatters the configuration a little, it'll reduce the risk that the silencing of deprecations gets updated in one part of our build but not another.

[github-actions]

📋 Stats

File sizes

File	Size
dist/govuk-frontend-development.min.css	118.41 KiB
dist/govuk-frontend-development.min.js	42.84 KiB
packages/govuk-frontend/dist/govuk/all.bundle.js	92.49 KiB
packages/govuk-frontend/dist/govuk/all.bundle.mjs	86.88 KiB
packages/govuk-frontend/dist/govuk/all.mjs	1.18 KiB
packages/govuk-frontend/dist/govuk/govuk-frontend-component.mjs	1.74 KiB
packages/govuk-frontend/dist/govuk/govuk-frontend.min.css	118.4 KiB
packages/govuk-frontend/dist/govuk/govuk-frontend.min.js	42.83 KiB
packages/govuk-frontend/dist/govuk/i18n.mjs	5.55 KiB
packages/govuk-frontend/dist/govuk/init.mjs	6.85 KiB

Modules

File	Size (bundled)	Size (minified)
all.mjs	82.55 KiB	40.37 KiB
accordion.mjs	26.44 KiB	13.33 KiB
button.mjs	8.95 KiB	3.71 KiB
character-count.mjs	24.57 KiB	10.6 KiB
checkboxes.mjs	7.81 KiB	3.42 KiB
error-summary.mjs	10.85 KiB	4.47 KiB
exit-this-page.mjs	20.06 KiB	10.26 KiB
header.mjs	6.46 KiB	3.22 KiB
notification-banner.mjs	9.21 KiB	3.63 KiB
password-input.mjs	18.11 KiB	8.26 KiB
radios.mjs	6.81 KiB	2.98 KiB
service-navigation.mjs	6.44 KiB	3.26 KiB
skip-link.mjs	6.4 KiB	2.76 KiB
tabs.mjs	12.04 KiB	6.67 KiB

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