D5237: fix: add suboption for configuring execution order of tools

[yuja (Yuya Nishihara)]

yuja added a comment.


  > +  When multiple tools are configured to affect a file, they execute in an order
  >  +  defined by the :priority suboption. The priority suboption has a default value
  >  +  of zero for each tool. Tools are executed in order of ascending priority.
  
  Appears that we use "descending" priority in hooks and merge-tools. Let's
  follow these. Other than that, the patch looks good to me.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D5237

To: hooper, #hg-reviewers
Cc: yuja, mercurial-devel