Make room model mandatory on the RoomHeader (#11355)

* Remove oobData from RoomHeader

It is never used as the RoomHeader is not shown unless a Room model exists

* Make room model mandatory on the RoomHeader

test/components/views/rooms/__snapshots__/RoomHeader-test.tsx.snap

@@ -1,44 +0,0 @@
-// Jest Snapshot v1, https://goo.gl/fbAQLP
-
-exports[`Roomeader renders with no props 1`] = `
-<DocumentFragment>
-  <header
-    class="mx_RoomHeader light-panel"
-  >
-    <span
-      class="mx_BaseAvatar"
-      role="presentation"
-    >
-      <span
-        aria-hidden="true"
-        class="mx_BaseAvatar_initial"
-        style="font-size: 26px; width: 40px; line-height: 40px;"
-      >
-        ?
-      </span>
-      <img
-        alt=""
-        aria-hidden="true"
-        class="mx_BaseAvatar_image"
-        data-testid="avatar-img"
-        loading="lazy"
-        src="data:image/png;base64,00"
-        style="width: 40px; height: 40px;"
-      />
-    </span>
-    <div
-      class="mx_RoomHeader_info"
-    >
-      <div
-        aria-level="1"
-        dir="auto"
-        role="heading"
-        style="font: var(--cpd-font-body-lg-semibold); letter-spacing: var(--cpd-font-letter-spacing-body-lg);"
-        title="Join Room"
-      >
-        Join Room
-      </div>
-    </div>
-  </header>
-</DocumentFragment>
-`;