[web] Updates package:web dependency to ^0.5.0. (#5791)
This PR updates the packages that are using package:web to version ^0.5.0.
Ancilliary changes:
* Bump environment to flutter: ">=3.19.0" and sdk: ^3.3.0.
* Bump version to next Y
* Clean-up code that was kept for compatibility with versions of web: <0.5.0.
The main exception to this is package:google_sign_in_web, which depends on a version of google_identity_services_web that has a dependency on package:web that is <0.5.0, so that package needs to have a range until google_identity_services_web gets published with the new ^0.5.0 dependency.
Co-Authored-By: David Iglesias<ditman@gmail.com>