Add RFC 9422 (LIMITS extension) support #70
Description
RFC 9422 adds LIMITS extension.
It is supported by Exim since version 4.98 and looks like this:
220 debian-exim ESMTP Exim 4.98 Tue, 03 Dec 2024 04:08:41 +0000
EHLO [127.0.0.1]
250-debian-exim Hello [127.0.0.1] [XXX]
250-SIZE 52428800
250-LIMITS MAILMAX=1000 RCPTMAX=50000
250-8BITMIME
250-PIPELINING
250-PIPECONNECT
250-CHUNKING
250-STARTTLS
250-PRDR
250 HELP
Parsed MAILMAX, RCPTMAX and RCPTDOMAINMAX limits should be exposed for the library user.