This removes the need for the remote counter.

We do not partially abstract the section info. Instead, we reuse the same
code in cook_constr and cook_constant and pass the same section info.

This fixes #8401
Supersedes / closes #8407

Vernacular-command-registered numeral notations now live in the summary,
and the interpretation function for them is hard-coded.

Plugin-registered numeral notations are still unsynchronized, and only
the UIDs of these functions gets synchronized.  I am not 100% sure why
this is fine, but the test-suite file working suggests that it is fine.
I think it is because worker delegation correctly handles
non-synchronized state which is declared at `Declare ML Module`-time.

This final commit changes the synchronization of numeral notations (and
deletes no-longer-used declarations in notation.mli that were introduced
temporarily in the last commit).  Since the interpretation can now be
done in notation.ml, we no longer need to register unique ids for
numeral notation (un)interp functions, and can instead synchronize the
underlying constants with the document state.  This is the change that
actually fixes #8401.

Print and Extraction commands may pierce opacity: if the
task producing the proof term is not finished, we wait for
its completion.
In -quick mode no worker is going to process a task, since tasks
are simply stored to disk (and resumed later in -vio2vo mode).

This commit avoids coqc waits forever for a task in order to
Print/Extract the corresponding term.  Bug reported privately
by Alec Faithfull.