templater: introduce top-level rule that wraps template terms

An epsilon rule will be moved here to disambiguate f() with f("").

src/commands/mod.rs

@@ -2915,7 +2915,7 @@ fn cmd_debug(
         }
         DebugCommands::Template(template_matches) => {
             let parse = TemplateParser::parse(
-                crate::template_parser::Rule::template,
+                crate::template_parser::Rule::program,
                 &template_matches.template,
             );
             writeln!(ui, "{parse:#?}")?;

src/template.pest

@@ -48,3 +48,5 @@ list = _{
 template = {
   whitespace* ~ (list | term | "") ~ whitespace*
 }
+
+program = _{ SOI ~ template ~ EOI }

src/template_parser.rs

@@ -381,17 +381,7 @@ pub fn parse_commit_template<'a>(
     workspace_id: &WorkspaceId,
     template_text: &str,
 ) -> Box<dyn Template<Commit> + 'a> {
-    let mut pairs: Pairs<Rule> = TemplateParser::parse(Rule::template, template_text).unwrap();
-
+    let mut pairs: Pairs<Rule> = TemplateParser::parse(Rule::program, template_text).unwrap();
     let first_pair = pairs.next().unwrap();
-    assert!(pairs.next().is_none());
-
-    assert_eq!(
-        first_pair.as_span().end(),
-        template_text.len(),
-        "failed to parse template past position {}",
-        first_pair.as_span().end()
-    );
-
     parse_commit_template_rule(repo, workspace_id, first_pair)
 }