pull: move `remote` argument into pull object One more step toward a more modular pull function.

pull: introduce a pulloperation object This object will hold all data and state gathered through the pull. This will allow us to split the long function into multiple small one. Smaller function will be easier to maintains and wrap. The idea is to blindly store all information related to the pull in this object so that each step and extension can use them if necessary. We start by putting the `repo` variable in the object. More migration in other function.

tests: lines with largefile .* file://$TESTTMP also match on windows on windows, largefile paths are written as "file:///C:/temp/...", corresponding to "file:///$TESTTMP/..." (all three slashes shown). But on posix systems they are written as "file:///tmp/..." corresponding to "file://$TESTTMP/..." (only two slashes shown). Write the glob "file:/*/" to match both versions.

debugobsolete: extract marker display in a dedicated function We want to be able to reuse and extend it from other function or extension while working on markers exchange. This changeset is pure core movement.

exchange: extract pull function from localrepo The localrepo class if far too big. Push and pull logic are extracted and reworked to better fit with the fact we exchange more than bundle now. This changeset extract the pulh code. later changeset will slowly slice it into smaller brick. The localrepo.pull method is kept for now to limit impact on user code. But it will be ultimately removed, now that the public API is hold by peer.

push: extract new common set computation from phase synchronisation Now that every necessary information is held in the `pushoperation` object, we can extract the new common set computation to it's own function. This changeset is pure code movement only.

push: move `commonheads` into the push object The phase synchronisation start by computing the new set of common head between local and remote and then do the phase synchronisation on this set. This new common set logic will eventually be used by the obsolescence markers exchange. So we are going to split the long phase synchronisation in two.

push: move discovery in its own function Now that every necessary information is held in the `pushoperation` object, we can extract the discovery logic to it's own function. This changeset is pure code movement only.