Deprecate legacy organisation colour palette

[querkmachine]

Deprecates the legacy organisation colour palette, which was replaced by an updated palette in 5.5.0.

Closes #5254.

Changes

• Deprecates the feature flag $govuk-new-organisation-colours in SassDoc.
• Deprecates the private variable that holds the legacy colours, $_govuk-legacy-organisation-colours, in SassDoc.
• Updates govuk-organisation-colour to produce a warning if the legacy colour palette is being used.

Thoughts

I wasn't entirely sure about how best to perform the deprecation, as the feature flag is only used to alter the default value of the $govuk-colours-organisations.

@romaricpascal suggested changing the variable assignment to use Sass's @if/@else structure to set the variable instead, but doing this caused some tests to fail, seemingly because assignment to $govuk-colours-organisations wasn't happening consistently. I also wasn't sure whether having the same variable with the !default flag defined multiple times might induce side effects, so I left this as is.

Ultimately, I added code to the govuk-organisation-colour function to produce a warning if the $govuk-new-organisation-colours feature flag is false. This doesn't help if someone is accessing $govuk-colours-organisations directly (which isn't uncommon), but it seems like the best option available.

[github-actions]

📋 Stats

File sizes

File	Size
dist/govuk-frontend-development.min.css	118.41 KiB
dist/govuk-frontend-development.min.js	42.7 KiB
packages/govuk-frontend/dist/govuk/all.bundle.js	92.81 KiB
packages/govuk-frontend/dist/govuk/all.bundle.mjs	87.12 KiB
packages/govuk-frontend/dist/govuk/all.mjs	1.25 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	42.69 KiB
packages/govuk-frontend/dist/govuk/i18n.mjs	5.55 KiB
packages/govuk-frontend/dist/govuk/init.mjs	7.13 KiB

Modules

File	Size (bundled)	Size (minified)
all.mjs	82.57 KiB	40.4 KiB
accordion.mjs	26.58 KiB	13.41 KiB
button.mjs	9.09 KiB	3.78 KiB
character-count.mjs	25.39 KiB	10.9 KiB
checkboxes.mjs	7.81 KiB	3.42 KiB
error-summary.mjs	10.99 KiB	4.54 KiB
exit-this-page.mjs	20.2 KiB	10.34 KiB
header.mjs	6.46 KiB	3.22 KiB
notification-banner.mjs	9.35 KiB	3.7 KiB
password-input.mjs	18.24 KiB	8.33 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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Action run for 9503bb7

[github-actions]

Other changes to npm package

diff --git a/packages/govuk-frontend/dist/govuk/helpers/_colour.scss b/packages/govuk-frontend/dist/govuk/helpers/_colour.scss
index 287c371ab..aed8dc949 100644
--- a/packages/govuk-frontend/dist/govuk/helpers/_colour.scss
+++ b/packages/govuk-frontend/dist/govuk/helpers/_colour.scss
@@ -75,6 +75,14 @@
     );
   }
 
+  // Output a deprecation warning if using the legacy colour palette
+  @if not $govuk-new-organisation-colours and not index($govuk-suppressed-warnings, "legacy-organisation-colours") {
+    @warn _warning-text("legacy-organisation-colours",
+      "The legacy organisation colour palette has been deprecated and will " +
+      "be removed in the next major version."
+    );
+  }
+
   $org-colour: map-get($govuk-colours-organisations, $organisation);
 
   @if map-has-key($org-colour, deprecation-message) and not index($govuk-suppressed-warnings, "organisation-colours") {
diff --git a/packages/govuk-frontend/dist/govuk/settings/_colours-organisations.scss b/packages/govuk-frontend/dist/govuk/settings/_colours-organisations.scss
index 12f976a45..b0a6f378d 100644
--- a/packages/govuk-frontend/dist/govuk/settings/_colours-organisations.scss
+++ b/packages/govuk-frontend/dist/govuk/settings/_colours-organisations.scss
@@ -11,6 +11,7 @@
 ///
 /// @type Boolean
 /// @access public
+/// @deprecated Using new organisation colours will become the default in Frontend v6.0.
 
 $govuk-new-organisation-colours: false !default;
 
@@ -211,6 +212,7 @@ $_govuk-organisation-colours: (
 ///   nor provide better contrast than the base colour.
 ///
 /// @access private
+/// @deprecated Migrate to using the new organisation colour palette instead.
 
 $_govuk-legacy-organisation-colours: (
   "attorney-generals-office": (

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Action run for 9503bb7