Add default binding for git pull

[wahtique]

Problem

No default command defined for git.pull.

Solution

Add default binding for git.pull.

My proposal would be to use <spc> g u for git update which would point to the command git.pull. I will attach a PR to this with this change.

Alternatives

Also considered either

• <spc> g P as which would place right next to <spc> g p Publish making it mnemonic but I don't really like the cap here
• <spc> g S for Sync but same objection as above and Sync isnt very close semantically to Status
• <spc> g g for Get which is nice since no other semantic is attached to g in this context. Might be my favorite if only I had already heard Get used instead of Sync, Update or Pull by anyone in any context

Alternative commands :

• git.pullRebase which looks like what I do most of the time ( or rather what GitKraken usually does for me ) but not sure if this usecase is more widespread than just git.pull
• git.pullFrom add another context menu but is more flexible than pull. I don't see myself pulling anything else than my current branch though

Additional context

Feels kinda bad to have all the other git commands but not this one which is pretty useful