feat: Add filter hook to stock status enum

[matthijs166]

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What does this implement/fix? Explain your changes.

Adds a filter hook to the Stock Status Enum so that there is the ability to add custom stock statues by developers

Does this close any currently open issues?

no

Any relevant logs, error output, GraphiQL screenshots, etc?

Any other comments?

Where has this been tested?

• WooGraphQL Version: 0.11.0
• WPGraphQL Version: 1.8.6
• WordPress Version: 6.0
• WooCommerce Version: 6.6.1

[codeclimate[bot]]

Code Climate has analyzed commit 54bc4f4e and detected 11 issues on this pull request.

Here's the issue category breakdown:

Category	Count
Style	11

The test coverage on the diff in this pull request is 100.0% (50% is the threshold).

This pull request will bring the total coverage in the repository to 76.4% (0.0% change).

View more on Code Climate.