basic lua snippet support (#1566)

Not nearly at the level of Python snippet support, but already quite
useful.

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Nicholas Riley <com-github@sabi.net>

core/snippets/snippets/elseIfStatement.snippet

@@ -20,3 +20,9 @@ language: python
 elif $1:
     $0
 ---
+
+language: lua
+-
+elseif $1 then
+    $0
+---

core/snippets/snippets/elseStatement.snippet

@@ -18,3 +18,9 @@ language: python
 else:
     $0
 ---
+
+language: lua
+-
+else
+    $0
+---

core/snippets/snippets/ifStatement.snippet

@@ -20,3 +20,10 @@ language: python
 if $1:
     $0
 ---
+
+language: lua
+-
+if $1 then
+    $0
+end
+---

core/snippets/snippets/lua.snippet

@@ -0,0 +1,21 @@
+language: lua
+---
+
+name: forInIPairs
+phrase: for eye pairs
+insertionScope: statement
+$1.insertionFormatter: SNAKE_CASE
+-
+for _, $1 in ipairs($2) do
+    $0
+end
+---
+
+name: forInPairs
+phrase: for pairs
+insertionScope: statement
+-
+for ${1:k}, ${2:v} in pairs($3) do
+    $0
+end
+---

core/snippets/snippets/ternary.snippet

@@ -11,3 +11,8 @@ language: python
 -
 $1 if $2 else $0
 ---
+
+language: lua
+-
+$1 and $2 or $0
+---