Fix NumberFormatException when creating JSON from llvm-cov 8.x output

[demirole]

When creating coverage with llvm-cov 8.0.1, the fields 'hasCount' and
'isRegionEntry' of class 'Segment' are output as booleans as oppose to integers in
previous versions.

This causes a java.lang.NumberFormatException when converting such a
JSON to XML:
Exception in thread "main" java.lang.NumberFormatException: For input string: "true"
at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:68)
at java.base/java.lang.Integer.parseInt(Integer.java:652)
at java.base/java.lang.Integer.parseInt(Integer.java:770)
at com.google.gson.JsonPrimitive.getAsInt(JsonPrimitive.java:264)
at com.olipro.utils.llvm.LLVMJSONSegment$LLVMJSONSegmentAdapter.deserialize(LLVMJSONSegment.java:22)
at com.olipro.utils.llvm.LLVMJSONSegment$LLVMJSONSegmentAdapter.deserialize(LLVMJSONSegment.java:14)

This commit fixes that error. In addition, it

• refactors TestLLVMJSON.java to read the test data from file
• adds a JSON dta file for llvm-cov 8.x output
• adds a class to provide the gsonBuilder

[demirole]

Hi Oliver,
I hope that you don't mind this PR. We are currently updating the whole LLVM toolset from 7 to 8 and stumbled over this issue with the changed output of Segments in JSON.
I should add that I am not a Java developer, so please let me know if this PR is nonsense.
Best, Levent