fix: Seek not applied in play method

[Dhanesh-Sawant]

Description

This PR is fixing the bug in which in web while initialising the play with duration specified, there was no seek happening, which means that it starts from the beginning itself. setting the source before calling seek in play() function, instead of setting it afterwards solves the issue, bec the AudioElement instance _player in wrappedPlayer class should be initailised before seeking.

Checklist

• The title of my PR starts with a Conventional Commit prefix (fix:, feat:, refactor:,
  docs:, chore:, test:, ci: etc).
• I have read the Contributor Guide and followed the process outlined for submitting PRs.
• I have updated/added tests for ALL new/updated/fixed functionality.
• I have updated/added relevant documentation and added dartdoc comments with ///, where necessary.
• I have updated/added relevant examples in example.

Breaking Change

• Yes, this is a breaking change.
• No, this is not a breaking change.

Related Issues

Closes #1597

[Dhanesh-Sawant]

@Gustl22 setting the source just before seek done👍

[Gustl22]

Thank you for contributing.
A few more notes:

• You checked the check box, that the title starts with a convential commit prefix, but it doesn't quite match the format :)
• You checked the check box, that you added tests, but there aren't any. This doesn't necessarily mean you have to provide them, but then also don't mark it as checked :)

This isn't anything fatal, but it facilitates our work and also hints the contributor about, what is still missing.
Theoretically if we don't provide tests, some day one can mistakenly revert your change without consequences and the bug will reoccur.

[Dhanesh-Sawant]

@Gustl22 done👍