Implement simple indents.scm for Elixir (#4821)

book/src/generated/lang-support.md

@@ -25,7 +25,7 @@
 | edoc | ✓ |  |  |  |
 | eex | ✓ |  |  |  |
 | ejs | ✓ |  |  |  |
-| elixir | ✓ | ✓ |  | `elixir-ls` |
+| elixir | ✓ | ✓ | ✓ | `elixir-ls` |
 | elm | ✓ |  |  | `elm-language-server` |
 | elvish | ✓ |  |  | `elvish` |
 | env | ✓ |  |  |  |

runtime/queries/elixir/indents.scm

@@ -0,0 +1,13 @@
+[
+  (after_block)
+  (anonymous_function)
+  (catch_block)
+  (do_block)
+  (else_block)
+  (rescue_block)
+  (stab_clause)
+] @indent
+
+[
+  "end"
+] @outdent