Fix issues with SMTP login mechanisms except "LOGIN"

[akhil1508]

Please check comment here

[the-djmaze]

Instead of revert, we could also disable SASLMechanisms.
Next release will already have more advanced per Domain setup to set certain IMAP settings there instead of global.

#724 (comment)

[akhil1508]

@the-djmaze So dropping OAUTHBEARER/XOAUTH2 support entirely? 😢

Or handling it in some other way?

[the-djmaze]

I mean, disable PLAIN for #423 and/or disable others as there are more broken IMAP servers between the issues.
As they are external issues, disabling broken SASL mechanisms should solve it.

Then this revert also makes sense without others needing plugins to disable mechanisms

[the-djmaze]

Made the change.
As of next release people with issue #693 and #423 can manually modify the sasl parts in data/_data_/_default_/domains/domain.tld.json

{
    "name": "domain.tld",
    "IMAP": {
        "host": "localhost",
        "port": 143,
        "type": 2,
        "timeout": 300,
        "shortLogin": false,
        "sasl": [
            "SCRAM-SHA3-512",
            "SCRAM-SHA-512",
            "SCRAM-SHA-256",
            "SCRAM-SHA-1",
            "PLAIN",
            "LOGIN"
        ],
        "ssl": {
            "verify_peer": true,
            "verify_peer_name": true,
            "allow_self_signed": false,
            "SNI_enabled": true,
            "disable_compression": true,
            "security_level": 1
        },
        "disable_list_status": false,
        "disable_metadata": false,
        "disable_move": false,
        "disable_sort": false,
        "disable_thread": false,
        "use_expunge_all_on_delete": false,
        "fast_simple_search": true,
        "force_select": false,
        "message_all_headers": false,
        "message_list_limit": 0,
        "search_filter": ""
    }
}

And also the "sasl" for SMTP and Sieve