templater: abstract ifcontains() over wrapped types
This allows us to make .keytype private.
There's a minor BC that a hybrid dict/list of keytype=None now strictly
checks the type of the needle. For example, {ifcontains(rev, files)} no longer
matches a file named "1" at the rev=1. I made this change for consistency
with the get(dict, key) function. We can restore the old behavior by making
keytype=bytes the default if desired.
$ hg init
$ echo 123 > a
$ hg add a
$ hg commit -m "first" a
$ mkdir sub
$ echo 321 > sub/b
$ hg add sub/b
$ hg commit -m "second" sub/b
$ cat sub/b
321
$ hg co 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ cat sub/b 2>/dev/null || echo "sub/b not present"
sub/b not present
$ test -d sub || echo "sub not present"
sub not present