[master]New Password Welcome form : Activate and choose intial password for new provisioned user

[compagnon]

Duplicate Proposal for #16245
(#16251 is pulled on stable 16 ( 16.0.1) )
pulled on MASTER ( $OC_VersionString = '17.0.0 alpha';)
Committer: same person - @gcompagnon @compagnon

/newpassword
/newpassword/email
/newpassword/userid
would provide a dedicated welcome page for new users , letting them enter the same process than Lost Password (new password feature is implemented into LostController)
This URL could be used into a customized Welcome email in a simple way for Business people/sales.

The new user could use that URL to choose his password, and the form could be customized to make user to accept conditions of use.

If the user has never login(is enabled) => this is a First connection

If the user returns, on that URL: this is a Lost Password form

• I have added also an administrator_email property on the config.php to display 'mailto' link to the * administrator email with the user id. l have updated some i10n messages for using that info instead of a "Administrator" , user knows the email.
• Anti spam is enabled with throttle_delay

Here is an exception management example: a mailto on the administrator email is enabled