Replay Support for Flutter Web

[buenaflor]

Please upvote this issue if you are interested in this feature

Since we have replay support for iOS and Android we can think about doing it for Flutter Web as well

On first glance we'd need to use a similar mechanism to iOS/Android which is using screenshots and mask widgets on top.

Notes:

• Flutter web is canvas based
• Theoretically we could use the native replay impl from the Javascript SDK which can also record canvases but that does not have masking