Compatibility with Jenkins 2.235

[Vlatombe]

Subsumes #21

Newer Jenkins pulls commons-codec 1.14 (from 1.12) which has slightly
different exception raised when certificate is invalid.

Test with
mvn test -Djenkins.version=2.235

Without the fix, you get the following error

Error Message
Unexpected exception, expected<org.jenkinsci.plugins.kubernetes.credentials.HttpClientWithTLSOptionsFactory$TLSConfigurationError> but was<java.lang.IllegalArgumentException>
Stacktrace
java.lang.Exception: Unexpected exception, expected<org.jenkinsci.plugins.kubernetes.credentials.HttpClientWithTLSOptionsFactory$TLSConfigurationError> but was<java.lang.IllegalArgumentException>
	at org.junit.internal.runners.statements.ExpectException.evaluate(ExpectException.java:28)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:365)
	at org.apache.maven.surefire.junit4.JUnit4Provider.executeWithRerun(JUnit4Provider.java:272)
	at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:236)
	at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:159)
	at org.apache.maven.surefire.booter.ForkedBooter.invokeProviderInSameClassLoader(ForkedBooter.java:386)
	at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:323)
	at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:143)
Caused by: java.lang.IllegalArgumentException: Last encoded character (before the paddings if any) is a valid base 64 alphabet but not a possible value. Expected the discarded bits to be zero.
	at org.apache.commons.codec.binary.Base64.validateCharacter(Base64.java:803)
	at org.apache.commons.codec.binary.Base64.decode(Base64.java:482)
	at org.apache.commons.codec.binary.BaseNCodecInputStream.read(BaseNCodecInputStream.java:163)
	at org.apache.commons.codec.binary.BaseNCodecInputStream.read(BaseNCodecInputStream.java:99)
	at sun.security.provider.X509Factory.readOneBlock(X509Factory.java:563)
	at sun.security.provider.X509Factory.engineGenerateCertificate(X509Factory.java:96)
	at java.security.cert.CertificateFactory.generateCertificate(CertificateFactory.java:339)
	at org.jenkinsci.plugins.kubernetes.credentials.HttpClientWithTLSOptionsFactory.loadFromString(HttpClientWithTLSOptionsFactory.java:56)
	at org.jenkinsci.plugins.kubernetes.credentials.HttpClientWithTLSOptionsFactory.getVerifyCertSSLFactory(HttpClientWithTLSOptionsFactory.java:76)
	at org.jenkinsci.plugins.kubernetes.credentials.HttpClientWithTLSOptionsFactory.getBuilder(HttpClientWithTLSOptionsFactory.java:88)
	at org.jenkinsci.plugins.kubernetes.credentials.HttpClientWithTLSOptionsFactoryTest.testThrowAnErrorOnInvalidCertificate(HttpClientWithTLSOptionsFactoryTest.java:21)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.internal.runners.statements.ExpectException.evaluate(ExpectException.java:19)
	... 16 more

[Vlatombe]

@maxlaverse can you review this?

[maxlaverse]

You probably know that better than me but it looks good. Thanks