Now that the lint engine can be extended, it becomes possible to run the
lint workflow mutliple times with a different configuration in order to
have some linters run in the desired order.

To do so the lint engine is changed between each workflow run, and a
separated configuration is read which contains the linters for the run.

This diffs introduce a new configuration file, .runlast.arclint. The
linters to be run last (sequentially after the other linters) are moved
from the .arclint configuration file to this one, currently
clang-format and autopep8. These linters are autofix linters which
apply to the whole file, thus leading to a 100% conflict rate with other
autofix linters.

Calling arc lint is now equivalent to runnint it twice, the first time
with all the linters excepted clang-format and autopep8, the second
time only with clang-format and autopep8.

The call to arc diff is also modified to match the arc lint
behavior.

Depends on D3298

Modify the src/init.cpp file. Add the line:

#include <stddef.h>

after the line:

#include <cstdint>

and before the line:

#include <cstdio>

Linting src/init.cpp now will result in a conflict, as clang-format
want to move the inclusion a line above to sort the includes, and the
cheader linter wants to replace stddeh.h with cstddef.
Before the patch, only the clang-format modification would have been
applied, after this patch, both are accounted:

arc lint --apply-patches -- src/init.cpp

arc diff --preview --trace

Check in the traces that the linters are run as expected.

arc diff --preview --trace --nolint

Check in the traces that no linter is run.