[html] Fix indentation when entering a newline while in the middle of a tag

Example:

```
        <tag>|</tag>
```
Then press enter

Old behaviour:
```
        <tag>
            </tag>
```
New behaviour:
```
        <tag>
        </tag>
```

I also added a test for it

1 files changed, 2 insertions, 2 deletions

diff --git a/rc/filetype/html.kak b/rc/filetype/html.kak
index 4a86e21b..33e65a9b 100644
--- a/rc/filetype/html.kak
+++ b/rc/filetype/html.kak
@@ -80,8 +80,8 @@ define-command -hidden html-indent-on-new-line %{
         try %{ execute-keys -draft <semicolon> K <a-&> }
         # filter previous line
         try %{ execute-keys -draft k : html-trim-indent <ret> }
-        # indent after lines ending with opening tag
-        try %{ execute-keys -draft k <a-x> <a-k> <lt>(?!area)(?!base)(?!br)(?!col)(?!command)(?!embed)(?!hr)(?!img)(?!input)(?!keygen)(?!link)(?!menuitem)(?!meta)(?!param)(?!source)(?!track)(?!wbr)(?!/)(?!>)[a-zA-Z0-9_-]+[^>]*?>$ <ret> j <a-gt> } }
+        # indent after lines ending with opening tag except when it starts with a closing tag
+        try %{ execute-keys -draft k <a-x> <a-k> <lt>(?!area)(?!base)(?!br)(?!col)(?!command)(?!embed)(?!hr)(?!img)(?!input)(?!keygen)(?!link)(?!menuitem)(?!meta)(?!param)(?!source)(?!track)(?!wbr)(?!/)(?!>)[a-zA-Z0-9_-]+[^>]*?>$ <ret>j<a-x><a-K>^\s*<lt>/<ret><a-gt> } }
 }
 
 ]