[IMP] mail_environment: Keep existing settings at install of module

[rven]

The Outgoing / Incoming mail servers configuration in the Odoo environment, will get lost when the mail_environment module gets installed.

With this change, a post installation hook is added which will add the current values to the server_env_defaults.
So the currently configured and working mail servers will still be working after the installation of this module.

[github-actions]

There hasn't been any activity on this pull request in the past 4 months, so it has been marked as stale and it will be closed automatically if no further activity occurs in the next 30 days.
If you want this PR to never become stale, please ask a PSC member to apply the "no stale" label.

[github-actions]

There hasn't been any activity on this pull request in the past 4 months, so it has been marked as stale and it will be closed automatically if no further activity occurs in the next 30 days.
If you want this PR to never become stale, please ask a PSC member to apply the "no stale" label.

[rven]

Still relevant

[petrus-v]

Nice one ! thanks

[OCA-git-bot]

This PR has the approved label and has been created more than 5 days ago. It should therefore be ready to merge by a maintainer (or a PSC member if the concerned addon has no declared maintainer). 🤖