`allow-newer` in project file `package` stanza

[bgamari]

While updating my projects for, e.g. a new compiler, I often find it necessary to vendorize libraries while waiting for upstream to merge bound bump changes. This is a fair amount of work, but I find it more satisfying than the alternative of just accumulating entries in the global allow-newer list.

What I would really like is a way to easily lift a given bound in particular package from within a project file. For instance,

package safecopy
    allow-newer: vector

[ezyang]

This is pretty easy to work around, so I'm not putting this as a release blocker.

[hvr]

@bgamari fyi, #3171 (comment) :-)

[hvr]

Now that #4669 got merged, the following wildcard variants would be useful

package safecopy
    -- ignore all `^>=` upper bounds declared in `safecopy`
    -- equivalent to a top-level `allow-newer: safecopy:^*` declaration
    allow-newer: ^*

package safecopy
    -- ignore upper `<` bounds defined in `safecopy`
    -- equivalent to a top-level `allow-newer: safecopy:*` declaration
    allow-newer: *