Why the httpclient5 and httpcore5 libraries are present in DITA-OT 4.1?

[jlacour31]

In DITA-OT 4.1 distribution there are 3 extra libraries:

• httpclient5-5.1.3.jar
• httpcore5-5.1.3.jar
• httpcore5-h2-5.1.3.jar

These libraries are brought into the distribution by xmlresolver-5.1.2.jar used in Saxon.
I think they can be excluded.

[jelovirt]

If only xmlresolver.org uses them and still works in all normal uses case without, we should remove them as bloat.

[jlacour31]

I created #4235 for removal.