tests: add a subdirectory to crlf tests

Add a subdirectory in the crlf.git bare repository that has a
second-level .gitattribute file.

tests/resources/crlf.git/COMMIT_EDITMSG

-Add .gitattributes

tests/resources/crlf.git/config

 [core]
 	repositoryformatversion = 0
-	bare = true
+	filemode = true
+	bare = false
+	logallrefupdates = true
+	ignorecase = true
+	precomposeunicode = true
+[remote "origin"]
+	url = /Users/ethomson/libgit2/libgit2-3/tests/resources/crlf.git
+	fetch = +refs/heads/*:refs/remotes/origin/*
+[branch "master"]
+	remote = origin
+	merge = refs/heads/master

tests/resources/crlf.git/logs/HEAD

-5afb6a14a864e30787857dd92af837e8cdd2cb1b 6b9d5748663795f573ea857276eb2a5f8330efa0 Edward Thomson <ethomson@edwardthomson.com> 1561324263 +0100	commit: Add .gitattributes
+0000000000000000000000000000000000000000 6b9d5748663795f573ea857276eb2a5f8330efa0 Edward Thomson <ethomson@edwardthomson.com> 1563721143 +0100	clone: from /Users/ethomson/libgit2/libgit2-3/tests/resources/crlf.git
+6b9d5748663795f573ea857276eb2a5f8330efa0 124f4293444614aa8da53be149792c2e43e9bfd9 Edward Thomson <ethomson@edwardthomson.com> 1563721187 +0100	commit: subdir with no translation

tests/resources/crlf.git/logs/refs/heads/master

-5afb6a14a864e30787857dd92af837e8cdd2cb1b 6b9d5748663795f573ea857276eb2a5f8330efa0 Edward Thomson <ethomson@edwardthomson.com> 1561324263 +0100	commit: Add .gitattributes
+0000000000000000000000000000000000000000 6b9d5748663795f573ea857276eb2a5f8330efa0 Edward Thomson <ethomson@edwardthomson.com> 1563721143 +0100	clone: from /Users/ethomson/libgit2/libgit2-3/tests/resources/crlf.git
+6b9d5748663795f573ea857276eb2a5f8330efa0 124f4293444614aa8da53be149792c2e43e9bfd9 Edward Thomson <ethomson@edwardthomson.com> 1563721187 +0100	commit: subdir with no translation

tests/resources/crlf.git/logs/refs/remotes/origin/HEAD

+0000000000000000000000000000000000000000 6b9d5748663795f573ea857276eb2a5f8330efa0 Edward Thomson <ethomson@edwardthomson.com> 1563721143 +0100	clone: from /Users/ethomson/libgit2/libgit2-3/tests/resources/crlf.git

tests/resources/crlf.git/packed-refs

+# pack-refs with: peeled fully-peeled sorted 
+9687e444bcbb85645cb496080434c292f1b57182 refs/remotes/origin/empty-files
+6b9d5748663795f573ea857276eb2a5f8330efa0 refs/remotes/origin/master

tests/resources/crlf.git/refs/heads/master

-6b9d5748663795f573ea857276eb2a5f8330efa0
+124f4293444614aa8da53be149792c2e43e9bfd9

tests/resources/crlf.git/refs/remotes/origin/HEAD

+ref: refs/remotes/origin/master