Fix unsafe implementation to generate cert aliases

[runeflobakk]

Implementation was based on an assumption that a path string obtained from a classpath URL can always be converted
to a Path instance, which is not the case, esp. on Windows.

Doing e.g. Paths.get("file:/C:/path/WEB-INF/lib/lib.jar!/file/in/jar") will make
sun.nio.fs.WindowsPathParser throw an InvalidPathException.

The bug was introduced by yours truly in v6.1:
https://github.com/digipost/signature-api-client-java/blob/6.1/src/main/java/no/digipost/signature/client/core/internal/security/TrustStoreLoader.java#L89
Will backport this fix to v6.1.1.

Exception stacktrace

no.digipost.signature.client.core.exceptions.ConfigurationException: Unable to load certificate from classpath: /certificates/test/Buypass_Class_3_Test4_CA_3.cer
at no.digipost.signature.client.core.internal.security.TrustStoreLoader$ClassPathResourceLoader.forEachFile(TrustStoreLoader.java:91)
at no.digipost.signature.client.core.internal.security.TrustStoreLoader.loadCertificatesInto(TrustStoreLoader.java:54)
at no.digipost.signature.client.core.internal.security.TrustStoreLoader.build(TrustStoreLoader.java:37)
at no.digipost.signature.client.ClientConfiguration.getSSLContext(ClientConfiguration.java:157)
at no.digipost.signature.client.core.internal.http.SignatureHttpClientFactory.create(SignatureHttpClientFactory.java:17)
at no.digipost.signature.client.portal.PortalClient.<init>(PortalClient.java:37)

...
Caused by: java.nio.file.InvalidPathException: Illegal char <:> at index 4: file:/C:/path/WEB-INF/lib/lib.jar!/certificates/test/Buypass_Class_3_Test4_CA_3.cer
at java.base/sun.nio.fs.WindowsPathParser.normalize(WindowsPathParser.java:182)
at java.base/sun.nio.fs.WindowsPathParser.parse(WindowsPathParser.java:153)
at java.base/sun.nio.fs.WindowsPathParser.parse(WindowsPathParser.java:77)
at java.base/sun.nio.fs.WindowsPath.parse(WindowsPath.java:92)
at java.base/sun.nio.fs.WindowsFileSystem.getPath(WindowsFileSystem.java:229)
at java.base/java.nio.file.Path.of(Path.java:147)
at java.base/java.nio.file.Paths.get(Paths.java:69)
at no.digipost.signature.client.core.internal.security.TrustStoreLoader$ClassPathResourceLoader.forEachFile(TrustStoreLoader.java:89)

[simenstoa]

🙆‍♂️