Remove the `basic_` prefix from valptridx<T>::basic_ptr, ::basic_idx,
and ::basic_ptridx. Since the public names are typedef aliases of these
classes, these class names appear frequently in debug information and
error messages. The `basic_` prefix is unnecessary. Remove it.
git grep -lz '\<basic_\(ptr\|ptridx\|idx\)\>' -- common/include/ | xargs -0 sed -i -e 's/\<basic_\(ptr\|ptridx\|idx\)\>/\1/g'
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