Add unit tests for literal tilde tokens in JSONPointer

[fahadaldajani92]

Add a single regression test method covering every input in #1081: string and URI-fragment pointers for ~01 and ~00, embedded escapes in a~01b and a~00b, builder tokens ~1 and ~0, and a token-list constructor containing ~1. Distinct values for the literal and formerly selected keys make the expected behavior explicit. Arrays.asList represents the list case while retaining the project's Java 8 compatibility.

Testing: ./gradlew test --tests org.json.junit.JSONPointerTest.escapedTildeTokensSelectLiteralKeys --no-daemon --console plain and ./gradlew clean build test --no-daemon --console plain passed using Temurin 11. The full run reported 814 tests, 0 failures, 0 errors, and 6 skipped. git diff --check passed.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[stleary]

What problem does this code solve?
Adds unit tests for JSONPointer

Risks
None

Changes to the Existing Behavior
N/A

Changes to the API
N/A

Will this require a new release?
No

Should the documentation be updated?
No

Unit Tests
Yes, the only change is new unit tests

Refactoring
No

Review status
APPROVED

Omitting 3-day comment period since nothing production-related was touched.