RFR: 8354053: Remove unused JavaIOFilePermissionAccess [v2]

[Roger Riggs]

On Mon, 14 Apr 2025 16:14:03 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

>> The JavaIOFilePermissionAccess interface is removed from SharedSecrets and its implementation (FilePermCompat.java) used by the test is moved to java.io FilePermission where cross package access is not needed. 
>> The test FilePermissionCollectionMerge is updated to access the internal implementation in FilePermission. 
>> Modernized the initialization from the system property `jdk.io.permissionsUseCanonicalPath`. 
>> The remaining support will be removed when FilePermission is removed.
>
> Roger Riggs has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Simplify as suggested in review comments
>   Convert static methods to instance methods and invoke on the existing FilePermission.

Note: FilePermissionCollectionMerge has never worked when `jdk.io.permissionsUseCanonicalPath=true`.
The creation of the alternate FilePermission gets an NPE because the internal npath is null.
And still does not; it is not worth fixing since FilePermission is to be removed.

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PR Comment: https://git.openjdk.org/jdk/pull/24603#issuecomment-2802221485