* feat: custom __link_optins

* chore: linter fixes

* test: add ui test for custom link option

(cherry picked from commit 1aa3f75d4c)

Co-authored-by: Himanshu <himanshuwarekar@yahoo.com>

(cherry picked from commit 42a3fe0fa2)

(cherry picked from commit db2e898397)

(cherry picked from commit b01929405d)

# Conflicts:
#	frappe/contacts/doctype/gender/gender.json
#	frappe/contacts/doctype/salutation/salutation.json

(cherry picked from commit 40f27f908a)

- Fixes [Issue/15324](https://github.com/frappe/frappe/issues/15324)
- When selecting a value for Link Field, the English text was set as link field value.
- This PR aims to fix it by setting the translated text as link field value on selection.

Todo:

- [x] Show translated text in the select dropdown
- [x] Set translated value to Link field on select
- [x] Show original value when link field is in focus
- [x] Add option to toggle this behaviour

### Behaviour

- Link field loses focus: show the translated name.
- Link field is focused
    - If old value is present
        - If options **are** one of [Role, DocType]: show the translated name
        - Else: show the name (untranslated) to enable search in untranslated values
    - Else: show what the user typed (untranslated) to enable search in untranslated values
- Value is selected: link field loses focus

## Demo

### Link to UOM in a custom Item DocType

The UOM names are in english, so the search needs to happen in english. When possible, the translation is displayed.

#### Before

https://user-images.githubusercontent.com/14891507/156415248-e5e80d05-53dc-4ca8-89c7-998986ff6e99.mov

#### After

https://user-images.githubusercontent.com/14891507/156410386-a874430c-f340-43ed-9c3a-92e8d4d50fc9.mov

### Link to DocType in Customize Form

The DocType names get translated before being searched. This is a preexisting hack in the framework for DocType and Role. In this case, we can search in the translations.

#### Before

https://user-images.githubusercontent.com/14891507/156414648-8e505f8c-9dee-4358-8182-3b358c28bb62.mov

#### After

https://user-images.githubusercontent.com/14891507/156411881-c4ca22e1-1397-4e13-9768-5e16b72f8d6d.mov

https://docs.erpnext.com/docs/v13/user/manual/en/customize-erpnext/customize-form/edit?wiki_page_patch=fdafee2715

* test: Add UI test for Link control

- Add API cy.call
- Add API cy.create_records
- Add ui_test_helpers.py

* style: Missing semicolon

* style: Missing semicolon

* style: Missing semicolon

* style: Remove unused imports

* test: Robust test for setting invalid value

* style: Remove unused import