Consider supporting *.mysql file type for import-db

[rfay]

What happened (or feature request):

Rick noted with a ddev demo that an import of a backup-migrate module backup failed. For example, ddev import-db --src=APLVDatabaseBackup-2017-10-23T06-30-32.mysql.gz:

Failed to import database for aplv: no .sql files found to import

The issue here is that backup-migrate uses the very nonstandard ".mysql" file type inside the gzip file, and ddev recognizes only the more-likely ".sql" filetype.

backup-migrate has gzip files like APLVDatabaseBackup-2017-10-23T06-30-32.mysql.gz containing a file like APLVDatabaseBackup-2017-10-23T06-30-32.mysql. If you gunzip and give the .mysql file to ddev import-db, it imports just fine.

It shouldn't be hard to expand our vision to looking for *.mysql as equivalent to *.sql

[rickmanelius]

We can re-open if anyone else trips up on this.

[nigelwhite]

As a frequent user of backup_migrate for its one-click downloads of remote databases (and I can't be the only one) this would be a big help.

[rfay]

Please open a new issue with your request, thanks!

[nigelwhite]

Done #1483