Partial put - enhance content range verification

[Chenjp]

per rfc 9110 - 14.4

• ContentRange - add isValid(), more length check.
• ContentRange - parse(): make sure the not-null return of parse() is valid.
• force content-range unit in lowercase internally.
• TestDefaultServletPut - cover issues by adding 2 sets of parameters.

[rmaucher]

-1
Other that the lower case range, the shuffling around of the checks introduces a much more serious bug (&& length > end).

[Chenjp]

-1 Other that the lower case range, the shuffling around of the checks introduces a much more serious bug (&& length > end).

A Content-Range field value is invalid if it contains a range-resp that has a last-pos value less than its first-pos value, or a complete-length value less than or equal to its last-pos value.

[rmaucher]

Ok, that's correct, the end is also inclusive.