Auto merge of #15674 - asajeffrey:test-wpt-html-editing-dir-ini, r=jgraham

Support running ./mach test-wpt /html.

<!-- Please describe your changes on the following line: -->

At the moment, running `./mach test-wpt /html` fails, because it runs the tests blocked by `include.ini`. This PR replaces the `include.ini` entry by `__dir__.ini` files in each subdirectory of `html/editing` apart from `html/editing/activation`.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes do not require tests because we don't watch the watchmen

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tests/wpt/include.ini

@@ -31,10 +31,6 @@ skip: true
   skip: false
 [html]
   skip: false
-  [editing]
-    skip: true
-    [activation]
-      skip: false
 [js]
   skip: false
 [navigation-timing]

tests/wpt/metadata/html/editing/assigning-keyboard-shortcuts/__dir__.ini

@@ -0,0 +1 @@
+disabled: for now

tests/wpt/metadata/html/editing/dnd/__dir__.ini

@@ -0,0 +1 @@
+disabled: for now

tests/wpt/metadata/html/editing/editing-0/__dir__.ini

@@ -0,0 +1 @@
+disabled: for now

tests/wpt/metadata/html/editing/focus/__dir__.ini

@@ -0,0 +1 @@
+disabled: for now

tests/wpt/metadata/html/editing/inert-subtrees/__dir__.ini

@@ -0,0 +1 @@
+disabled: for now

tests/wpt/metadata/html/editing/the-hidden-attribute/__dir__.ini

@@ -0,0 +1 @@
+disabled: for now