Switch to Jakarta Mail

[mkurz]

Just a reminder to switch from javax.mail.* to jakarta.mail.* and from javax.activation.* to jakarta.activation.* when possible.
This depends on commons-email however:

• Migrate to jakarta package namespace ( and commons-email2 ) apache/commons-email#133
• Bump jakarta.mail from 1.6.5 to 2.0.1 apache/commons-email#43
• upgrade jakarta.mail to 2.0.0 (rename javax.mail -> jakarta.mail) apache/commons-email#37

Probably Angus Mail will be used as implemention of Jakarta Mail 2.x.

(BTW: Also check this line in play-grpc, not sure if or when we should change that exclude.)