Add plural form for flower farming variant unit names

[tschumilas]

⚠️ Please use clockify code #12476 Flower Farms

Description

- As a: shopper
- On page: /permalink/shop and /admin/products
- I want to be able to do:

Flower farms use some variant unit names that currently appear as singular only (as the user entered them).

Variant name plural are hard coded for now see #4709

List of singular unit names in English:
bucket (buckets)
pail (pails)
stem (stems)
plug (plugs)
plant (plants)
bundle (bundles)
bulb (bulbs)
root (roots)
tuber (tubers)
corm (corms)

Acceptance Criteria & Tests

1. Go to admin -> products.
2. Change a product to items instead of weight or volume.
3. Add a unit name that matches the list above
4. Change the quantity including 0, 1 and 2 of the variant and observe the change in the description.
5. Save the changes.
6. Go to the shopfront and verify the variant display there.

[RachL]

@chahmedejaz this can be a quick one before jumping on something bigger.

I wanted to add a more specific example, but I've noticed the plurals I gave here #4172 (comment) Do not work anymore.

Maybe this is something that is handled differently now?

[RachL]

Or maybe this is something that got lost with BUU? 🤔

[chahmedejaz]

Sure, Rachel. I'll take a look at it 👍🏻