Fix #799 - Sieve as a Thunderbird plug broken

[dxdxdt]

• Accommodate nsIMsgIncomingServer interface change
• https://hg.mozilla.org/comm-central/rev/e7602ee8cf16b8885dcc63d6f70650223b26260f

[thsmi]

Thank you for posting this patch but this issue was fixed on the Thunderbird 102 compatibility pull request in commit e827edcd8b0a1fdaf1f4134b0490f1c4629c79f1

Sadly the new version broke way more stuff than just this issue. If you refer to the pull request you can see that it contains changes for ~170 files. And it is still not in a state where it could be released and would pass the addon review process.

As this is already fixed on the TB102 compatibility branch, I'll close this pull request as a duplicate.