[AltTester Editor] Tests list minor assembly-related issues

[iulianatodoran]

Steps to reproduce

1. Open the AltTester Unity SDK project from the GitHub repo in each Unity version (mentioned in the Additional info section)
2. Open the AltTester Editor window and check the Tests list

Actual result

AR

1. ❌ in Unity 2020 and 2022 the test DefaultTestExample.txt located in Assets/AltTester/Editor is not displayed at all in the Tests list
2. ❌ in Unity 2021 the same test DefaultTestExample.txt is misplaced in the AltTester.AltTesterUnitySDK assembly
3. ❌ there is one assembly category that is not displayed in Unity 2020 and 2022 LTS: AltTester.AltTesterUnitySDK

Additional info

Environment

• SampleGame project with AltTester Unity SDK from development branch
• Unity v 2020.3.48f1 LTS, 2021.3.25f1 LTS, 2022.3.5f1 LTS

Expected result

ER

1. in Unity 2020 and 2022 the test DefaultTestExample.txt should be placed in its correspondent AltTester.AltTesterUnitySDK.Editor assembly category from the Tests list
2. in Unity 2021 the test DefaultTestExample.txt should be placed in its correspondent AltTester.AltTesterUnitySDK.Editor assembly
3. in Unity 2020 and 2022 the AltTester.AltTesterUnitySDK assembly category should be displayed regardless if it contains or not test scripts

Additional info

Testability