Rename conflict revset to conflicts.

See discussion thread in linked issue.

With this PR, all revset functions in [BUILTIN_FUNCTION_MAP](https://github.com/martinvonz/jj/blob/8d166c764251042287626ab37a1148386cef8371/lib/src/revset.rs#L570)
that return multiple values are either named in plural or named in a difficult-to-misused manner (e.g. `reachable`)

Fixes: #4122

CHANGELOG.md

@@ -14,6 +14,9 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
   commit to commit. It now either follows the flags `--edit|--no-edit` or it
   gets the mode from `ui.movement.edit`.
 
+* `conflict` revset has been renamed to `conflicts`. With this, all revsets that
+  could potentially return multiple results are named in the plural.
+
 ### Deprecations
 
 ### New features

docs/revsets.md

@@ -296,7 +296,7 @@ given [string pattern](#string-patterns).
   For example, `diff_contains("TODO", "src")` will search revisions where "TODO"
   is added to or removed from files under "src".
 
-* `conflict()`: Commits with conflicts.
+* `conflicts()`: Commits with conflicts.
 
 * `present(x)`: Same as `x`, but evaluated to `none()` if any of the commits
   in `x` doesn't exist (e.g. is an unknown branch name.)

lib/src/revset.rs

@@ -773,7 +773,7 @@ static BUILTIN_FUNCTION_MAP: Lazy<HashMap<&'static str, RevsetFunction>> = Lazy:
             RevsetFilterPredicate::DiffContains { text, files },
         ))
     });
-    map.insert("conflict", |function, _context| {
+    map.insert("conflicts", |function, _context| {
         function.expect_no_arguments()?;
         Ok(RevsetExpression::filter(RevsetFilterPredicate::HasConflict))
     });

lib/tests/test_revset.rs

@@ -3439,7 +3439,7 @@ fn test_evaluate_expression_conflict() {
 
     // Only commit4 has a conflict
     assert_eq!(
-        resolve_commit_ids(mut_repo, "conflict()"),
+        resolve_commit_ids(mut_repo, "conflicts()"),
         vec![commit4.id().clone()]
     );
 }