[18.0][MIG] fs_image_thumbnail: Migration to 18.0

[xaviedoanhduy]

depend on: #446

Note: this is a technical module so it is quite difficult to test the functionality on the UI. so I encourage everyone to follow the steps I tested below to create records in Fs Image Thumbnails:

$ ./odoo.sh shell

>>>import base64

>>>from odoo.addons.fs_image.fields import FSImageValue

>>>attachment = self.env['ir.attachment'].create({
...     'name': 'test',
...     'datas': base64.b64encode(open('/home/trobz/Pictures/my/Heart-shaped-glasses.jpeg', 'rb').read()),
... })
>>>image_value = FSImageValue(attachment)

>>>thumbnails = self.env['fs.thumbnail'].get_or_create_thumbnails(image_value, sizes=[(800,600), (400, 200)], base_name='my')

>>>env.cr.commit()

1. check in: menu Settings >> Technical >> Database Structure >> Attachments

2. check in: menu Settings >> Technical >> FS Storage >> Fs Thumbnail

[lmignon]

/ocabot migration fs_image_thumbnail

[kobros-tech]

@xaviedoanhduy

There is a conflict!