feat(frontend): Add option for plugins to add header actions (#9570)

* [FR] PUI - Add option for plugins to add header actions
Fixes #8593

* fix parsing

* fix merge

* reduce diff

* fix sample implementation

* add support for icons and colors in primary actions

* add changelog entry

* add docs

* add more detailed sample text

* pass location into context

* fix test

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Co-authored-by: Oliver <oliver.henry.walters@gmail.com>

CHANGELOG.md

@@ -23,6 +23,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - [#11778](https://github.com/inventree/InvenTree/pull/11778) adds inline supplier part creation to po line item addition dialog.
 - [#11772](https://github.com/inventree/InvenTree/pull/11772) the UI now warns if you navigate away from a note panel with unsaved changes
 - [#11788](https://github.com/inventree/InvenTree/pull/11788) adds support for custom permissions checks on database models defined in plugins. If a model defines a `check_user_permission` classmethod, this will be called to determine if a user has permission to view the model. This is required for plugin models which do not have the required ruleset definitions for the standard permission system.
+- [#9570](https://github.com/inventree/InvenTree/pull/9570) adds support for defining primary actions via plugins
 
 ### Changed