Rex::Text::uri_encode - make 'hex-all' really mean all.

'hex-all' encoding was previously ignoring slashes.
This pull adds 'hex-noslashes' mode which carries forward the previous functionality, and replaces all existing references to 'hex-all' with 'hex-noslashes'  It then adds a replacement 'hex-all' mode, which really encodes *ALL* characters.
Adds spec for 'hex-all' mode
Fix up spec.  Rex::Proto::Http::ClientRequest handles & and = outside of Rex::Text::uri_encode, so mode doesn't affect them.

Fix erroneous typo char.
Add 'u-noslashes' and re-order cases for consistency.
Update comment w/ all modes
Land #3353, @jjarmoc's Rex::Text::uri_encode improvements