Improve error reporting when the API fails to parse the returned content properly

org.xwiki.rendering.macro.MacroExecutionException: Failed to retrieve JIRA data from [https://mysite.atlassian.net] for JQL [issueKey in (MYPROJECT-13070)]
	at org.xwiki.contrib.jira.macro.internal.source.AbstractJIRADataSource.getXMLDocument(AbstractJIRADataSource.java:96)
	at org.xwiki.contrib.jira.macro.internal.source.ListJIRADataSource.getData(ListJIRADataSource.java:78)
	at org.xwiki.contrib.jira.macro.internal.JIRAMacro.execute(JIRAMacro.java:87)
	at org.xwiki.contrib.jira.config.internal.AsyncJIRAMacro.executeCodeMacro(AsyncJIRAMacro.java:92)
	at org.xwiki.contrib.jira.config.internal.JIRABlockAsyncRenderer.execute(JIRABlockAsyncRenderer.java:110)
	at org.xwiki.rendering.async.internal.block.AbstractBlockAsyncRenderer.render(AbstractBlockAsyncRenderer.java:157)
	at org.xwiki.rendering.async.internal.block.AbstractBlockAsyncRenderer.render(AbstractBlockAsyncRenderer.java:54)
	at org.xwiki.rendering.async.internal.AsyncRendererJob.runInternal(AsyncRendererJob.java:109)
	at org.xwiki.job.AbstractJob.runInContext(AbstractJob.java:243)
	at org.xwiki.job.AbstractJob.run(AbstractJob.java:220)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:829)
Caused by: org.jdom2.input.JDOMParseException: Error on line 1: Content is not allowed in prolog.
	at org.jdom2.input.sax.SAXBuilderEngine.build(SAXBuilderEngine.java:232)
	at org.jdom2.input.sax.SAXBuilderEngine.build(SAXBuilderEngine.java:253)
	at org.jdom2.input.SAXBuilder.build(SAXBuilder.java:1091)
	at org.xwiki.contrib.jira.macro.internal.source.HTTPJIRAFetcher.retrieveRemoteDocument(HTTPJIRAFetcher.java:108)
	at org.xwiki.contrib.jira.macro.internal.source.HTTPJIRAFetcher.fetch(HTTPJIRAFetcher.java:73)
	at org.xwiki.contrib.jira.macro.internal.source.AbstractJIRADataSource.getXMLDocument(AbstractJIRADataSource.java:94)
	... 12 more
Caused by: org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 1; Content is not allowed in prolog.
	at org.apache.xerces.util.ErrorHandlerWrapper.createSAXParseException(Unknown Source)
	at org.apache.xerces.util.ErrorHandlerWrapper.fatalError(Unknown Source)
	at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source)
	at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source)
	at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source)
	at org.apache.xerces.impl.XMLScanner.reportFatalError(Unknown Source)
	at org.apache.xerces.impl.XMLDocumentScannerImpl$PrologDispatcher.dispatch(Unknown Source)
	at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
	at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
	at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
	at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
	at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
	at org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown Source)
	at org.jdom2.input.sax.SAXBuilderEngine.build(SAXBuilderEngine.java:217)
	... 17 more