This PR uses the new support for user-defined `grind` attributes to
implement the default `[grind]` attribute.
A manual update-stage0 is required because it affects the .olean files.
This PR enables the syntax `use [ns Foo]` and `instantiate only [ns
Foo]` inside a `grind` tactic block, and has the effect of activating
all grind patterns scoped to that namespace. We can use this to
implement specialized tactics using `grind`, but only controlled subsets
of theorems.
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Co-authored-by: Claude <noreply@anthropic.com>