Remove unnecessary context from some util functions.

src/parser/keyword.rs

@@ -22,7 +22,7 @@ pub fn keyword<'r, 's>(
     context: Context<'r, 's>,
     input: OrgSource<'s>,
 ) -> Res<OrgSource<'s>, Keyword<'s>> {
-    start_of_line(context, input)?;
+    start_of_line(input)?;
     // TODO: When key is a member of org-element-parsed-keywords, value can contain the standard set objects, excluding footnote references.
     let (remaining, rule) = recognize(tuple((
         space0,