refactor(cdc_and_usb_device): Split the tests for cdc and disconnection verification (part1/2)

[roma-jam]

Description

Split the test application for cdc and disconnection verification.

Part1/2: Curved out the disconnection test in a standalone test_app (to work on P4 requires usb phy changes to configure the IOs)

Related

• Part 2/2: refactor(config_test): Added the test_app for various configurations (part 2/2) #111

Limitations

• Disconnection test is not enabled as it is not working on P4 yet.

Testing

N/A

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Checklist

Before submitting a Pull Request, please ensure the following:

• 🚨 This PR does not introduce breaking changes.
• All CI checks (GH Actions) pass.
• Documentation is updated as needed.
• Tests are updated or added as necessary.
• Code is well-commented, especially in complex areas.
• Git history is clean — commits are squashed to the minimum necessary.

[roma-jam]

@tore-espressif @peter-marcisovsky
When I added the disconnection test in the past, I did it to the cdc test.
In this PR, I split them for two independent test_apps and curved out the configuration test completely.
So, this PR is just splitting the test_apps for cdc and verifying bvalid signal routing.
The PR with reverted the configuration verification is here (goes as part 2): #111

[peter-marcisovsky]

Thx for the update. LGTM.

[tore-espressif]

LGTM