feat: linking supplier with an item group for filtering items

[noahjacob]

Changes:

• Created a doctype to create links between supplier and item_groups.

• Updated filters for buying module if any item groups are linked to the supplier.
  
  (If no item groups are linked to the supplier it does not apply the filter)

• Added Supplier Item Group in Supplier dashboard.
  

• Docs

[rohitwaghchaure]

@noahjacob add supplier item group doctype in the dashboard of supplier

[rohitwaghchaure]

frappe.get_list checks whether the user has permission of Supplier Item Group or not, if the person who is creating the purchase order has not permission of the doctype Supplier Item Group then system will not allowed user to make the purchase order and throw below error.

You can use frappe.get_all instead of frappe.get_list because in this case we don't need to check permission for the doctype 'Supplier Item Group'

[barredterra]

@noahjacob, @rohitwaghchaure filters argument is a string containing json, when called from the frontend. The following code breaks with this PR:

frappe.call({
    method: 'erpnext.controllers.queries.item_query',
    args: {
        doctype: 'Item',
        txt: '',
        searchfield: 'name',
        start: 0,
        page_len: 99,
        filters: {
            supplier: 'Unico Plastics Inc.',
            is_sales_item: 1
        },
        as_dict: true
    },
    callback: (r) => console.log(r.message)
});

filters string needs to be parsed to json first.

Please fix or revert this PR.

[nabinhait]

already fixed via #25915 , will release in sometime

[barredterra]

@nabinhait while it doesn't produce an error anymore, filters will still be ignored in my example.