Use a fallback classloader suitable for java Modules or OSGi environments.

[wglas85]

When loading TerminalProviders in context using java Modules or OSGi, the fallback to the system classloader in

jline3/terminal/src/main/java/org/jline/terminal/spi/TerminalProvider.java

Line 57 in 114e9a8

cl = ClassLoader.getSystemClassLoader();

is inappropriate ands leads to load errors inside TerminalProvider.

The more appropriate fallback classloader is

   TerminalProvider.class.getClassLoader()

which points to the system classloader in simple setups or to the module's or OSGi bundle classloader in more complex deployments.