Add inline Giphy and direct GIF previews for Boost comments

[brealorg]

Adds an optional Boost for Reddit patch that restores inline Giphy previews in comment threads and also supports direct .gif links such as i.redd.it/*.gif.

Behavior:

• Giphy links in comments are rendered as inline previews.
• Direct .gif links are rendered as inline previews.
• Tapping the preview area keeps Boost's normal comment collapse/expand behavior.
• Tapping the source/Open Giphy line opens the external source.

Implementation notes:

• Injects at the start of CommentViewHolder.o(...) to avoid verifier/register reuse issues.
• Syncs preview visibility with comment collapse state through CommentViewHolder.w(I).
• Avoids adding the preview directly to the item root fallback, since that caused blank/oversized layout artifacts in Boost comment rows.
• Keeps the source label visible and clickable to avoid interfering with the preview/collapse behavior.

Tested with:

• Boost for Reddit 1.12.12
• Morphe Android app
• Clean APK input
• Giphy comment previews
• Direct i.redd.it/*.gif previews
• Comment collapse/expand
• Basic comment-thread scrolling

This patch has also been tested in a temporary external hotfix bundle before opening this PR.