further limits discoverability of resetAttrs

This commit removes resetAllAttrs from the public reflection API.
This method was previously deprecated, but on a second thought that
doesn't do it justice. People should be aware that resetAllAttrs is just
wrong, and if they have code that uses it, this code should be rewritten
immediately without beating around the bush with deprecations. There's
a source-compatible way of achieving that (resetLocalAttrs), so that
shouldn't bring much trouble.

Secondly, resetAllAttrs in compiler internals becomes deprecated. In subsequent
commits I'm going to rewrite the only two locations in the compiler that
uses it, and then I think we can remove it from the compiler as well.
does away with resetAllAttrs in the reifier

resetLocalAttrs works just fine there
does away with resetAllAttrs in typedLabelDef

Again, resetLocalAttrs works just fine there - no need to destroy
references to externally defined symbols.
SI-8248 kills resetAllAttrs

Noone uses it anymore, so I'm rushing to remove it, so that it no longer
can trick people into using it.
renames resetLocalAttrs to resetAttrs

Now when resetAllAttrs is gone, we can use a shorter name for the one
and only resetLocalAttrs.
Merge pull request #3485 from xeno-by/topic/reset-all-attrs

kills resetAllAttrs