Change product landing page introLinks to a general map of link titles to links (#26360)

* Add cta button to frontmatter and context

* Add cta to Page

* Render cta button in product landing hero

* Handle external links

* Add simple unit test for cta link

* Address feedback

Co-authored-by: Peter Bengtsson <mail@peterbe.com>

* Actually push condition update

* Show it's an external link

* Refactor FullLink so we use Link once

Co-authored-by: Peter Bengtsson <mail@peterbe.com>

* Custom link can also be null

* Rename 'cta' to 'custom' and make it the last introLink

* Update tests with 'cta' to 'custom' change

* Filter once

* Revert "Filter once"

This reverts commit a3f9a8a06b505d77fed47ca96a66c187c86c3c91.

* Update introLinks to a map of titles and URLs

* No more custom introLink in LandingHero

* Simplify introLinks processing

* introLinks can also be null

Co-authored-by: Peter Bengtsson <mail@peterbe.com>

* more concise

Co-authored-by: Peter Bengtsson <mail@peterbe.com>

* No longer necessary with the a plain introLinks map

Co-authored-by: Peter Bengtsson <mail@peterbe.com>

* '.entries()` is simpler

Co-authored-by: Peter Bengtsson <mail@peterbe.com>

* 'link' could be false depending on what version you're on

* Update test for new introLinks

Co-authored-by: Peter Bengtsson <mail@peterbe.com>

components/context/ProductLandingContext.tsx

@@ -38,11 +38,7 @@ export type ProductLandingContextT = {
   intro: string
   beta_product: boolean
   product: Product
-  introLinks: {
-    quickstart?: string
-    reference?: string
-    overview?: string
-  } | null
+  introLinks: Record<string, string> | null
   product_video?: string
   featuredLinks: Record<string, Array<FeaturedLink>>
   productCodeExamples: Array<CodeExample>
@@ -128,13 +124,7 @@ export const getProductLandingContextFromRequest = (req: any): ProductLandingCon
       })
     ),
 
-    introLinks: page.introLinks
-      ? {
-          quickstart: page.introLinks.quickstart,
-          reference: page.introLinks.reference,
-          overview: page.introLinks.overview,
-        }
-      : null,
+    introLinks: page.introLinks || null,
 
     featuredLinks: getFeaturedLinksFromReq(req),