Revert "Remove ChrootPaths class"

This reverts commit 31fd5803ed957a8152728208c770e10580f8c7d8.

Reason for revert: Breaks a bunch of unittests:

ERROR: [chromite.service.sdk_unittest] CreateTest.testCreate
AttributeError: 'CreateArguments' object has no attribute 'paths'

FAIL: [chromite.api.controller.sdk_unittest] SdkCreateTest.testTrueArguments
AssertionError: Expected call: CreateArguments(replace=False, bootstrap=True, use_image=False, paths=<ANY>)
Actual call: CreateArguments(replace=False, bootstrap=True, use_image=False, cache_dir='', chroot_path='')

Original change's description:
> Remove ChrootPaths class
> 
> This class only had two fields that can easily just be passed as args.
> 
> BUG=None
> TEST=None
> 
> Change-Id: I41716b009975cd01479949adca02d802d9614aaf
> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2044991
> Tested-by: Chris McDonald <cjmcdonald@chromium.org>
> Commit-Queue: Chris McDonald <cjmcdonald@chromium.org>
> Reviewed-by: Alex Klein <saklein@chromium.org>

Change-Id: Ie1761dbb875dd089e70259cda7f3f5d4e0400cf0
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2049184
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
diff --git a/api/controller/sdk_unittest.py b/api/controller/sdk_unittest.py
index dff3589..01b6203 100644
--- a/api/controller/sdk_unittest.py
+++ b/api/controller/sdk_unittest.py
@@ -96,6 +96,19 @@
     args_patch.assert_called_with(replace=False, bootstrap=True,
                                   use_image=False, paths=mock.ANY)
 
+  def testPathArguments(self):
+    """Test the path arguments handling."""
+    # Create the patches.
+    self.PatchObject(sdk_service, 'Create', return_value=1)
+    paths_patch = self.PatchObject(sdk_service, 'ChrootPaths')
+
+    # Test the path arguments get passed through.
+    cache_dir = '/cache/dir'
+    chroot_path = '/chroot/path'
+    request = self._GetRequest(cache_path=cache_dir, chroot_path=chroot_path)
+    sdk_controller.Create(request, self.response, self.api_config)
+    paths_patch.assert_called_with(cache_dir=cache_dir, chroot_path=chroot_path)
+
 
 class SdkUpdateTest(cros_test_lib.MockTestCase, api_config.ApiConfigMixin):
   """Update tests."""