tdf#153487 First color item needs mnId = 1

The SvxColorValueSet for the other color palettes is build so that the
first item gets value 1 in its mnId component. But for the new theme
color palette it was 0. That results in the error, that the first
color (top-left in the dialog) could not be selected. An Id of value 0
is handled as 'fail' in various places. Thus use starting mnId = 1 for
theme color palette too.

Change-Id: Ic0b63fee641d4424cabaf25a7f803acd734cbfa3
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/153860
Tested-by: Jenkins
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>
(cherry picked from commit cf13f9d89b4411b8c2b38bb3eb1ac4e6346b5b74)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/153925
diff --git a/svx/source/tbxctrls/PaletteManager.cxx b/svx/source/tbxctrls/PaletteManager.cxx
index 607bd60..9fcefd34 100644
--- a/svx/source/tbxctrls/PaletteManager.cxx
+++ b/svx/source/tbxctrls/PaletteManager.cxx
@@ -207,7 +207,7 @@ void PaletteManager::ReloadColorSet(SvxColorValueSet &rColorSet)
            auto pColorSet = pObjectShell->GetThemeColors();
            mnColorCount = 12;
            rColorSet.Clear();
            sal_uInt16 nItemId = 0;
            sal_uInt16 nItemId = 1;

            if (!pColorSet)
                return;