On the one hand, SvxZoomSliderItem/SvxZoomSliderControl as used by SwView's
SID_ATTR_ZOOMSLIDER support a range from MINZOOM (20) to MAXZOOM (600) (defined
in sw/inc/view.hxx).  Setting a zoom value outside that range for one causes the
DBG_ASSERT "Looks like the zoom slider item is corrupted" in
SvxZoomSliderControl::StateChanged (svx/source/stbctrls/zoomsliderctrl.cxx) to
fire, and for another (when setting a too small value) tries to assign a
negative value (which wraps around, and gets flagged by Clang's
-fsanitize=implicit-signed-integer-truncation) to sal_uInt16 nCurrentZoom at

  nCurrentZoom = nCurrentZoom - mxImpl->mnMinZoom;

in SvxZoomSliderControl::Zoom2Offset (svx/source/stbctrls/zoomsliderctrl.cxx).

On the other hand, SwXViewSettings' support of css.text.ViewSettings' ZoomValue
property allowed values in the range from 5 to 1000 (cf.
SwXViewSettings::_setSingleValue in sw/source/uibase/uno/unomod.cxx), and some
JunitTests actually set such values (10, 15) below the MINZOOM value of 20.

The incompatible 5--1000 range was there ever since
7b0b5cdf "initial import", but looks rather
random, so change it to match the 20--600 range instead.  (And lets flag this as
an [API CHANGE], to be on the safe side.)

One of the JunitTests files that needed to be adapted,
qadevOOo/tests/java/mod/_sw/SwAccessibleEndnoteView.java, oddly mentioned a
zoom value of 130% in a comment while using the value 15 in the actual code.
(And did so ever since the test code's introduction in
26ebdfc4 "NEW: initial version".)  Changing the
code to 130 would cause JunitTest_sw_unoapi_1 to fail in strange ways, with
disposed UNO objects, while changing the code (and comment) to 21 appears to
work.  Go figure.

Change-Id: Id944ffdce501448312e008436e7038bf2aec63ac
Reviewed-on: https://gerrit.libreoffice.org/67427
Tested-by: Jenkins
Reviewed-by: Samuel Mehrbrodt <Samuel.Mehrbrodt@cib.de>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>