Business Manager: Introduction of Business Manager class and changes in template tool according to it

BusineeTemplate: Add fixes for Business Manager installation to work with BT installation during bootstrap

(fix: e46ade7a)

(fix erp5.git/eb5f1fb1)

As it is a common pattern to set validators on hidden fields
to display custom errors to users.

By using `os.path.normpath` we also support paths with a trailing slash.

Also, change the JSON format and update tests according to these changes

The script though that user was scrolling the test output while in reality we just
add a tiny difference of 0.5 pixel.

/reviewed-on nexedi/erp5!632

Fixes dropbox app key in officejs media player.

/reviewed-on nexedi/erp5!628