feat(filters): add squish filter (#943)

docs/source/_data/sidebar.yml

@@ -94,6 +94,7 @@ filters:
   sort: sort.html
   sort_natural: sort_natural.html
   split: split.html
+  squish: squish.html
   strip: strip.html
   strip_html: strip_html.html
   strip_newlines: strip_newlines.html

docs/source/filters/squish.md

@@ -0,0 +1,18 @@
+---
+title: squish
+---
+
+{% since %}v10.28.0{% endsince %}
+
+Removes leading and trailing whitespace from a string, and replaces every run of whitespace inside it with a single space.
+
+Input
+```liquid
+{{ "  Hello   there,
+    Major Tom.  " | squish }}
+```
+
+Output
+```text
+Hello there, Major Tom.
+```