Imported mails are deleted too late from the offline storage

[abdulkadir-tutao]

Describe the bug
Mails are deleted based on the timestamp on the mailIds. However, for imported emails, this causes them to be deleted too late since the received date on the mail is older than the date encoded to their mailId (date of creation (import)).

Expected behavior
Mails are deleted from the offline storage in an appropriate time. There are two different approaches:

• Delete based on received date
• Keep as-is to store imported mails. Users can see their imported mails more quickly after importing them since they'll already be stored in the offline storage.

Version [261.250116.0]

Additional context
MailOfflineCleaner.ts