RFR: 7903965: Fix Launching Tests from Context Menu [v2]

[Oleksii Sylichenko]

> Currently, there is an issue with running TestNG/JUnit tests when using the context menu on the editor tab. TestNG/JUnit intercepts the test execution from JTReg.
> 
> After fixing this issue, I decided to extend the fix to cover all potential use cases of the context menu.
> 
> As part of this pull request, I propose enhancing the process of running tests via the context menu. The context menu can be used in the following cases:
> 
> - Editor tab
> - File in the project tree
> - Directory in the project tree
> - Any location within a file
> 
> The current changes automatically determine what needs to be executed:
> 
> - Directory
> - File
> - Method
> 
> Additionally, the issue with intercepting test execution through Application, TestNG, and JUnit configurations when using the context menu on the editor tab has been fixed.
> 
> # Summary
> 
> - Ensure that run configuration priority is no longer lost to Application, TestNG, or JUnit setups when launching via the context menu.  
> - Fix run configuration created via the context menu: find and launch the proper test element, depending on the current PSI element.  
> - Improve the logic for comparing existing run configurations with newly generated ones.  
> - Add JUnit plugin in the dependencies.
> 
> # Detailed changes
> 
> ## Add JUnit plugin into dependencies
> - build.gradle
> - plugin.xml
> 
> ## JTRegClassConfigurationProducer.java
> - Refactor `setupConfigurationFromContext`:
>   - Move the check for whether a file can be run to `JTRegUtils#isRunnableByJTReg`.  
>   - Allow this method to create configurations for directories as well.  
>   - Implement `preventRunPriorityLoss` to prevent priority takeover by other run configuration types (Application, TestNG, JUnit) under certain conditions.  
>   - Replace the use of the current PSI element for generating names and querying run configurations with the specific element intended for execution.  
> - Implement `preventRunPriorityLoss`.
> - Add Javadoc for `nameForElement`.
> 
> ## JTRegConfigurationProducer.java
> - Fix logic in `isConfigurationFromContext` for checking if two configurations are identical:
>   - Replace the use of the current PSI element for queries with the exact element intended for execution.  
> - Compare string-typed configuration parameters using a "not-nullify" approach (`null == ""`).
> - Implement `findExactRunElement` to locate the specific PSI element for execution among the current element’s parents.
> - Add a JUnit check to the `shouldReplace` method.
> 
> ## JTRegUtils.java
> - Add a predicate to compare two strings ...

Oleksii Sylichenko has updated the pull request incrementally with one additional commit since the last revision:

  JTRegClassConfigurationProducer: add `null` check for `setRunClass` case

-------------

Changes:
  - all: https://git.openjdk.org/jtreg/pull/252/files
  - new: https://git.openjdk.org/jtreg/pull/252/files/b7ff1422..3a3f1019

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jtreg&pr=252&range=01
 - incr: https://webrevs.openjdk.org/?repo=jtreg&pr=252&range=00-01

  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jtreg/pull/252.diff
  Fetch: git fetch https://git.openjdk.org/jtreg.git pull/252/head:pull/252

PR: https://git.openjdk.org/jtreg/pull/252