Drop std::as_const from css::uno::Sequence iterations

Obsoleted by commit 2484de6728bd11bb7949003d112f1ece2223c7a1 (Remove non-const Sequence::begin()/end() in internal code, 2021-10-15) and commit fb3c04bd1930eedacd406874e1a285d62bbf27d9 (Drop non-const Sequence::operator[] in internal code, 2021-11-05). Change-Id: Idbafef5d34c0d4771cbbf75b9db9712e504164cd Reviewed-on: https://gerrit.libreoffice.org/c/core/+/162640 Tested-by: Jenkins Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

This change is not about speed improvements but diverse
preparations to make changes/reading/understanding easier.
It does not change speed AFAIK.

Added a global static debug-only counter to allow getting
an overview over number of all allocated SfxPoolItem's
and the still alloated ones at office shutdown. The values
are used in Application::~Application to make a short info
statement. It allows to be able to quickly detect if an
error in future changes may lead to memory losses - these
would show in dramaitically higher numbers then (hopefully)
immediately.

Moved SfxVoidItem to own source/header.

Added container library interface support to SfxItemSet,
adapted already some methods to use it - not all possible,
I will commit & get status from gerrit 1st if all still works
and then continue.

Changed INVALID_POOL_ITEM from -1 to use a global unique
incarnation of an isolated derivation from SfxPoolItem. It
allows to avoid the (-1) pointer hack. Since still just
pointers are compared it's not worse. NOTE: That way, more
'special' SfxPoolItem's may be used for more States - a
candidate is e.g. SfxVoidItem(0) which represents ::DISABLED
state -- unfortunately not only, it is also used (mainly for
UI stuff) with 'real' WhichIDs - hard to sort out, will have
to stay that way for now AFAIK.

Changed INVALID_POOL_ITEM stuff to use a static extern
incarnated item in combination with a inline method
to return it, called GetGlobalStaticInvalidItemInstance().

Isolated create/cleanup of a SfxPoolItem entry in
SfxItemSet to further modularize/simplify that. It is
currently from constructor & destructor but already shows
that PoolDefaults are handled differently - probably an
error. Still, for now, do no change in behaviour (yet).

Got regular 'killed by the Kill-Wrapper' messages from
gerrit, seems to have to do with UITest_sw_findReplace.
That python/c++ scripting stuff is hard to debug, but
finally I identified the problem has to do with
the INVALID_POOL_ITEM change. It was in
SfxItemSet::InvalidateAllItems() where still a (-1)
was used -> chaos in detecting invalid items.

Change-Id: I595e1f25ab660c35c4f2d19c233d1dfadfe25214
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/155675
Tested-by: Jenkins
Reviewed-by: Armin Le Grand <Armin.Le.Grand@me.com>

OUStringLiteral should be declared constexpr, to enforce that it is initialised at compile-time and not runtime. This seems to make a different at least on Visual Studio Change-Id: I1698f5fa22ddb480347c2f4d444530c2e0e88d92 Reviewed-on: https://gerrit.libreoffice.org/c/core/+/153499 Tested-by: Jenkins Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

Standardize on OUString, which is the main internal string class. Convert from/to OUString only when communicating with respective external APIs. Removes about 200 conversions from the code. Change-Id: I96ecee7c6fd271bb76639220e96d69d2964bed26 Reviewed-on: https://gerrit.libreoffice.org/c/core/+/149930 Tested-by: Jenkins Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

make the plugin more conservative, so we see less false+ (although we also miss some possibilities in the process) Change-Id: I91b1806271e7f802d7459834ab7bcc569047da3a Reviewed-on: https://gerrit.libreoffice.org/c/core/+/137342 Tested-by: Jenkins Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>