Make it possible to opt out of Session Replay dependencies (which now includes libwebp)

[jverkoey]

Problem Statement

3.19.0 added a dependency on libwebp for the Replay engine.

Solution Brainstorm

Would love it if Replay was a dependency that you could add as an extension to the core PostHog analytics library!

[ioannisj]

Hey @jverkoey!

Thank for the suggestion! I do agree that making replay an optional extension would be a great enhancement, especially for users concerned about growing SDK size. That said, it does introduce a few challenges:

• Some of our SDKs depend on this native SDK, so decoupling replay might require additional changes to those SDKs as well.
• Making replay optional would mean users need to handle an additional dependency if they choose to install it separately. It may also complicate setup just a bit.
• This change would also break backward compatibility, meaning it would require a major version release.

That said, I’d love to gather more feedback on this so I'll leave this open for anyone to upvote.

Just a note that we’ve vendored libwebp and stripped unnecessary features like encoding and animated WebP support, so the impact on SDK size should be minimal.