Rework stripping binaries when copying to containers

We now only attempt to strip binaries, by detecting the
LINKFLAGS variable on the targets.

CopySetHaikuRevision now also forwards LINKFLAGS
to revisioned binaries.

Introduce separate AppendToContainerCopyFilesScriptStripFile actions
which are used for copying and stripping, and avoids many useless
shell tests.

When asked to strip binaries, they are detected and handled
individually for simplicity.

Note we still don't keep resources and attributes when stripping.