Feature(sitemap): named files chunking strategy

[Slackluky]

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New sitemap optional configuration for named sitemap files chunking strategy

Adds a chunks option to the sitemap configuration schema.
This allows users to define custom chunking strategies for
generating sitemaps, providing flexibility in how the sitemap
is split into multiple files.

			integrations: [
				sitemap({
					serialize(item) {
						return item
					},
					chunks: {
						'blog': (item) => {
							if (/blog/.test(item.url)) {
								item.changefreq = 'weekly';
								item.lastmod = new Date();
								item.priority = 0.9;
								return item;
							}
						},
						'glossary': (item) => {
							if (/glossary/.test(item.url)) {
								item.changefreq = 'weekly';
								item.lastmod = new Date();
								item.priority = 0.9;
								return item;
							}
						}
					},
				}),
			],

Testing

Docs

yes, to add optional configurations for the chunks

@withastro/maintainers-docs for feedback!

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[ascorbic]

Is this a breaking change?

[Slackluky]

no, it only add an optional chunk configuration in sitemap integration, i have added a testing file and fixture to sitemap integration module and all tests passed successfully

[ascorbic]

Why does this need the Promise.resolve()?

[Slackluky]

The Promise.resolve() call is indeed necessary in this case. The callback function cb provided in the chunks option can return either a direct SitemapItem object or a Promise that resolves to a SitemapItem object. Promise.resolve() ensures that the result is always a Promise, allowing for consistent handling of both synchronous and asynchronous results.