feat: add url and name to alp admin overview

[ahuininga-orisha]

Summary

• Adds a Store URLs column to the landing page admin grid, showing each store's URL path prefixed with the store name (e.g. Global: my-landing-page). Store ID 0 is labelled Global.
• Replaces the Name column with store-scoped names from emico_attributelanding_page_store, rendered with the same store_id prefix as the URL column.
• Both columns are searchable via a HAVING GROUP_CONCAT(...) LIKE ? clause, avoiding issues with aggregate expressions in WHERE.
• Fixes a pre-existing bug where the grid showed one row per store per page (due to an inner join in Page\Collection); the grid now always shows one row per landing page with all store values grouped.
• Introduces Model\ResourceModel\Page\Grid\Collection, a dedicated grid collection extending SearchResult, keeping grid-specific query logic isolated from the general-purpose Page\Collection used on the frontend.

How to test

Scenario 1 — Store URLs and Names are visible

1. Go to Content > Landing Pages in the admin.
2. Confirm the grid shows a Name column and a Store URLs column.
3. For a landing page configured on multiple stores, confirm both columns show one line per store prefixed with the store name (e.g. Global: my-url, Default Store View: my-url).
4. For a landing page with only a global (store_id = 0) row, confirm the prefix reads Global.

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Scenario 2 — One row per landing page

1. Create a landing page and save it for at least two store views.
2. Open the landing page grid.
3. Confirm the page appears once in the grid, not once per store.

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Scenario 3 — Searching on Store URLs

1. In the Store URLs filter field at the top of the grid, type part of a known URL path.
2. Confirm only matching landing pages are returned.
3. Confirm no SQL error occurs and pagination works correctly.

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Scenario 4 — Searching on Name

1. In the Name filter field, type part of a known landing page name.
2. Confirm only matching landing pages are returned.
3. Confirm no SQL error occurs and pagination works correctly.

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Scenario 5 — Frontend is unaffected

1. Visit a landing page URL on the storefront (e.g. https://magento2.test/default/women/tops-women2/).
2. Confirm the page loads correctly with filters applied as before.
3. Confirm no regression in URL matching or filter behaviour.

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