User defined states (#7862)

* Add custom user defined states

* make tests more reliable

* fix list options

* Adapt version

* do not engage if rebuilding

* remove unneeded attr

* remove unneeded attr

* fix enum imports

* adapt cove target

* Add status_custom_key to all other serializers

* fix serializer method

* simplify branching

* remove unneeded imports

* inherit read_only status from leader field

* Add more tests

* fix tests

* add test for function

* refactor for easier testing

* move test to seperate class

* Add options testing

* extend serializer

* add test for all states and refactor to reuse already build functions

* use custom field in PUI too

* reset diff

* style fix

* fix comparison

* Add test for str

* test color exceptions too

* remove user state from tracking

* Add intro from model fields too

* update docs

* simplify implementation

* update tests

* fix name

* rename test

* simplify tags and test fully

* extend test to machine status

* move logic for response formatting over

* extend api response with machine  status

* ensure only direct subclasses are discovered

* test for length of total respone too

* use new fields on PUI too

* fix test assertion with plugins enabled

* also observe rendering in filters

* Add managment endpoints and APIs

* Add contenttypes to PUI renderes

* use filteres instead

* fix import order

* fix api route definition

* move status choices to serializer

* fix lookup

* fix filtering

* remove admin integration

* cleanup migration

* fix migration change

* cleanup code location

* fix imports

* Add docs for custom states

* add links to custom status

docs/docs/order/purchase_order.md

@@ -38,6 +38,8 @@ Refer to the source code for the Purchase Order status codes:
         show_source: True
         members: []
 
+Purchase Order Status supports [custom states](../concepts/custom_states.md).
+
 ### Purchase Order Currency
 
 The currency code can be specified for an individual purchase order. If not specified, the default currency specified against the [supplier](./company.md#suppliers) will be used.

docs/docs/order/return_order.md

@@ -61,6 +61,8 @@ Refer to the source code for the Return Order status codes:
         show_source: True
         members: []
 
+Return Order Status supports [custom states](../concepts/custom_states.md).
+
 ## Create a Return Order
 
 From the Return Order index, click on <span class='badge inventree add'><span class='fas fa-plus-circle'></span> New Return Order</span> which opens the "Create Return Order" form.

docs/docs/order/sales_order.md

@@ -39,6 +39,8 @@ Refer to the source code for the Sales Order status codes:
         show_source: True
         members: []
 
+Sales Order Status supports [custom states](../concepts/custom_states.md).
+
 ### Sales Order Currency
 
 The currency code can be specified for an individual sales order. If not specified, the default currency specified against the [customer](./company.md#customers) will be used.