will look like with java 17 FFM Panama

Improved the toString methods.

Simplified BaseBuffer API.

And BaseBufferImpl to PositionalImpl.

Cleaned up some duplicate methods.

Improved some javadocs.

Corrected some tests that were referring to the wrong exception.

1. I have corrected the javadocs and code comments to use "off-heap"
instead of "direct" or "native". However, I decided not to change the
use of "Direct" in existing method calls or in the /internal/ directory.
That would cause a huge number of changes (100's).

2. I have corrected the javadocs and code comments to use "alive" or
"isAlive" instead of "valid" or "isValid". However, I decided not to
change the word "Valid" in the /internal/ directory.  That would cause a
huge number of changes (100's).