Integrate the new timeline renderer behind a feature flag (#7722)

* Integrate the new renderer with the timeline UI

* Composable functions are now in `:libraries:htmlrenderer:api` so we don't need to add `impl` to other modules.

* Improve inline code span

* Return both the text and URL in `onLinkClick` and `onLinkLongClick` so we can check the URL is not misleading

* Remove `SelectionContainer` for now - it creates issues when long pressing

* Make `LocalComposeTimelineEventRenderer` contain a `ComposeLocalTimelineEventRendererData` instance. This checks if the new rendering is enabled and what is the current user id so it can be used for styling mention pills

* Add fading edges to code block to indicate scrolling is possible

* Long pressing in a code block copies its contents to the clipboard

* Fix alignment of ordered list item prefixes

* Don't use default values in State data classes

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Co-authored-by: ElementBot <android@element.io>

libraries/ui-common/src/main/kotlin/io/element/android/libraries/ui/common/layout/ContentAvoidingLayout.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2026 Element Creations Ltd.
+ * Copyright (c) 2025 Element Creations Ltd.
  * Copyright 2023-2025 New Vector Ltd.
  *
  * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.