[ntp-realbox] Add feature flags for the 2 Tall realbox variants. This change refactors the `RealboxLayoutMode` enum to distinguish between two tall layouts for the Realbox. The existing "Tall" mode is now represented by "TallBottomContext" (context button displayed at the bottom of dropdown) and "TallTopContext" (context button displayed above the dropdown items). CSS and HTML templates are updated to apply the same styling to both new modes. Bug: b:448168842 Change-Id: I601cd80f511a64d75652c52ec7ff93e13edcf7a6 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7014528 Reviewed-by: Ananya Seelam <ananyaseelam@google.com> Commit-Queue: Dhruv Kathpalia <dhruvkathpalia@google.com> Reviewed-by: Roman Arora <romanarora@chromium.org> Cr-Commit-Position: refs/heads/main@{#1526975} NOKEYCHECK=True GitOrigin-RevId: 86d5e5eb88c7506e88103c0de47e3d2d6375ca90 1 file changed
