Encoding issue parsing with `mvn` Java files with unusual Character

[blacelle]

Seen in #912 (comment)

[WARNING] Issue reading /cleanthat-showcases/javaparser/javaparser-core-testing/src/test/resources/com/github/javaparser/TestFileIso88591.java
java.nio.charset.MalformedInputException: Input length = 3
    at java.lang.String.throwMalformed (String.java:1279)
    at java.lang.String.decodeUTF8_UTF16 (String.java:1166)
    at java.lang.String.newStringUTF8NoRepl (String.java:759)
    at java.lang.String.newStringNoRepl1 (String.java:790)
    at java.lang.String.newStringNoRepl (String.java:772)
    at java.lang.System$2.newStringNoRepl (System.java:2480)
    at java.nio.file.Files.readString (Files.java:3362)
    at eu.solven.cleanthat.code_provider.inmemory.FileSystemCodeProvider.safeReadString (FileSystemCodeProvider.java:179)
    at eu.solven.cleanthat.code_provider.inmemory.FileSystemCodeProvider.loadContentForPath (FileSystemCodeProvider.java:172)
    at eu.solven.cleanthat.mvn.codeprovider.OverlayCodeProviderWrite.loadContentForPath (OverlayCodeProviderWrite.java:81)
    at eu.solven.cleanthat.formatter.CodeProviderFormatter.loadCodeOptMutated (CodeProviderFormatter.java:430)
    at eu.solven.cleanthat.formatter.CodeProviderFormatter.doFormat (CodeProviderFormatter.java:388)
    at eu.solven.cleanthat.formatter.CodeProviderFormatter.lambda$onEachFile$9 (CodeProviderFormatter.java:361)
    at com.google.common.util.concurrent.TrustedListenableFutureTask$TrustedFutureInterruptibleTask.runInterruptibly (TrustedListenableFutureTask.java:131)
    at com.google.common.util.concurrent.InterruptibleTask.run (InterruptibleTask.java:76)
    at com.google.common.util.concurrent.TrustedListenableFutureTask.run (TrustedListenableFutureTask.java:82)
    at java.util.concurrent.Executors$RunnableAdapter.call (Executors.java:572)
    at java.util.concurrent.FutureTask.run (FutureTask.java:317)
    at java.util.concurrent.ThreadPoolExecutor.runWorker (ThreadPoolExecutor.java:1144)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run (ThreadPoolExecutor.java:642)
    at java.lang.Thread.run (Thread.java:1583)
[WARNING] Skip processing javaparser/javaparser-core-testing/src/test/resources/com/github/javaparser/TestFileIso88591.java as its content is not available
[WARNING] Issue reading /cleanthat-showcases/javaparser/javaparser-core-testing-bdd/src/test/resources/com/github/javaparser/samples/ClassInLatin1.java
java.nio.charset.MalformedInputException: Input length = 3
    at java.lang.String.throwMalformed (String.java:1279)
    at java.lang.String.decodeUTF8_UTF16 (String.java:1166)
    at java.lang.String.newStringUTF8NoRepl (String.java:759)
    at java.lang.String.newStringNoRepl1 (String.java:790)
    at java.lang.String.newStringNoRepl (String.java:772)
    at java.lang.System$2.newStringNoRepl (System.java:2480)
    at java.nio.file.Files.readString (Files.java:3362)
    at eu.solven.cleanthat.code_provider.inmemory.FileSystemCodeProvider.safeReadString (FileSystemCodeProvider.java:179)
    at eu.solven.cleanthat.code_provider.inmemory.FileSystemCodeProvider.loadContentForPath (FileSystemCodeProvider.java:172)
    at eu.solven.cleanthat.mvn.codeprovider.OverlayCodeProviderWrite.loadContentForPath (OverlayCodeProviderWrite.java:81)
    at eu.solven.cleanthat.formatter.CodeProviderFormatter.loadCodeOptMutated (CodeProviderFormatter.java:430)
    at eu.solven.cleanthat.formatter.CodeProviderFormatter.doFormat (CodeProviderFormatter.java:388)
    at eu.solven.cleanthat.formatter.CodeProviderFormatter.lambda$onEachFile$9 (CodeProviderFormatter.java:361)
    at com.google.common.util.concurrent.TrustedListenableFutureTask$TrustedFutureInterruptibleTask.runInterruptibly (TrustedListenableFutureTask.java:131)
    at com.google.common.util.concurrent.InterruptibleTask.run (InterruptibleTask.java:76)
    at com.google.common.util.concurrent.TrustedListenableFutureTask.run (TrustedListenableFutureTask.java:82)
    at java.util.concurrent.Executors$RunnableAdapter.call (Executors.java:572)
    at java.util.concurrent.FutureTask.run (FutureTask.java:317)
    at java.util.concurrent.ThreadPoolExecutor.runWorker (ThreadPoolExecutor.java:1144)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run (ThreadPoolExecutor.java:642)
    at java.lang.Thread.run (Thread.java:1583)

We may have to change some default Charset from UTF8 to UTF16.