Compatible with Commerce 5

[lukeholder]

Description

• Fixes price import mapping (should be importing to basePrice now)
• Adds support for updating inventory in the primary inventory location for the variant
• Moves the promotable, freeShipping, taxCategoryId, shippingCategoryId, availableForPurchaseto the variant (purchasable), and renamedhasUnlimitedStocktoinventoryTracked`

Related issues

#1439
#1428

[lukeholder]

To get the compatibility release early and test this PR, change your craftcms/feed-me requirement in composer.json to:

"require": {
  "craftcms/feed-me": "dev-feature/commerce-5-support as 6.0.1"
  "...": "..."
}

Then run composer update.

[angrybrad]

@lukeholder this all works on Craft 4 as well? i.e. since Feed Me 6 is Craft 5 specific, but Craft 5 also works with Commerce 4, should these changes apply to Craft 4 / Feed Me 5 as well?

//cc @i-just