[IMP] Inventory: Bringing reassign lot/serial numbers current

[fw-bot]

While updating tutorials around removal strategies and expiration dates, I noticed that the documentation around reassigning lots and serial numbers was outdated as of version 18.2. This PR completely rewrites the content, bringing it up to date with 18.2, and updates and adds screenshots.

This saas-18.2 PR should not be FWP past saas-18.4.

Forward-Port-Of: #15916

[robodoo]

[fw-bot]

@erjer-odoo cherrypicking of pull request #15916 failed.

stdout:

Auto-merging content/applications/inventory_and_mrp/inventory/product_management/product_tracking/reassign.rst
CONFLICT (content): Merge conflict in content/applications/inventory_and_mrp/inventory/product_management/product_tracking/reassign.rst
warning: Cannot merge binary files: content/applications/inventory_and_mrp/inventory/product_management/product_tracking/reassign/adjustment.png (af7ec4de3b3b6c107224c9e521bbd45d6d0de1d7 vs. 7541b37c39a0152a55be666752c84481b60fa2b2)
Auto-merging content/applications/inventory_and_mrp/inventory/product_management/product_tracking/reassign/adjustment.png
CONFLICT (content): Merge conflict in content/applications/inventory_and_mrp/inventory/product_management/product_tracking/reassign/adjustment.png
warning: Cannot merge binary files: content/applications/inventory_and_mrp/inventory/product_management/product_tracking/reassign/history.png (af7ec4de3b3b6c107224c9e521bbd45d6d0de1d7 vs. 7541b37c39a0152a55be666752c84481b60fa2b2)
Auto-merging content/applications/inventory_and_mrp/inventory/product_management/product_tracking/reassign/history.png
CONFLICT (content): Merge conflict in content/applications/inventory_and_mrp/inventory/product_management/product_tracking/reassign/history.png
warning: Cannot merge binary files: content/applications/inventory_and_mrp/inventory/product_management/product_tracking/reassign/remove-quant.png (af7ec4de3b3b6c107224c9e521bbd45d6d0de1d7 vs. 7541b37c39a0152a55be666752c84481b60fa2b2)
Auto-merging content/applications/inventory_and_mrp/inventory/product_management/product_tracking/reassign/remove-quant.png
CONFLICT (content): Merge conflict in content/applications/inventory_and_mrp/inventory/product_management/product_tracking/reassign/remove-quant.png
CONFLICT (modify/delete): content/applications/inventory_and_mrp/inventory/product_management/product_tracking/reassign/update-quantity.png deleted in af7ec4de3b3b6c107224c9e521bbd45d6d0de1d7 and modified in 7541b37c39a0152a55be666752c84481b60fa2b2.  Version 7541b37c39a0152a55be666752c84481b60fa2b2 of content/applications/inventory_and_mrp/inventory/product_management/product_tracking/reassign/update-quantity.png left in tree.

Either perform the forward-port manually (and push to this branch, proceeding as usual) or close this PR (maybe?).

In the former case, you may want to edit this PR message as well.

⚠️ after resolving this conflict, you will need to merge it via @robodoo.

More info at https://github.com/odoo/odoo/wiki/Mergebot#forward-port