Respect newlines in if/else and let expressions (#1259)

Change the formatter to prevent multiline if/else and let expressions
from collapsing into a single line.

pkl-formatter/src/test/files/FormatterSnippetTests/input/expr-if.pkl

@@ -5,3 +5,29 @@ foo =
     else
       if (someAnotherCondition) 30000
       else 4
+
+foo2 = if (bar) 1 else 2
+
+// respect newlines in if/else if they exist.
+// if anything of these wrap, everything wraps.
+foo3 =
+  if (bar)
+    1 else 2
+
+foo4 =
+  if (bar) 1 else 
+    2
+
+foo5 =
+  if (bar) 1
+  else 2
+
+foo6 =
+  if (bar)
+    1
+  else
+    2
+
+foo7 =
+  if /* some comment */ (bar) 1
+  else 2

pkl-formatter/src/test/files/FormatterSnippetTests/input/expr-let.pkl

@@ -15,3 +15,11 @@ qux = let ( // some comment
     bar = 5
   )
     bar
+
+quzzy =
+  let (baz = 1) baz + 1
+
+// respect newlines in lets
+quzzzy =
+  let (baz = 1)
+    baz + 1

pkl-formatter/src/test/files/FormatterSnippetTests/output/expr-if.pkl

@@ -7,3 +7,37 @@ foo =
     30000
   else
     4
+
+foo2 = if (bar) 1 else 2
+
+// respect newlines in if/else if they exist.
+// if anything of these wrap, everything wraps.
+foo3 =
+  if (bar)
+    1
+  else
+    2
+
+foo4 =
+  if (bar)
+    1
+  else
+    2
+
+foo5 =
+  if (bar)
+    1
+  else
+    2
+
+foo6 =
+  if (bar)
+    1
+  else
+    2
+
+foo7 =
+  if /* some comment */ (bar)
+    1
+  else
+    2

pkl-formatter/src/test/files/FormatterSnippetTests/output/expr-let.pkl

@@ -25,3 +25,10 @@ qux =
     bar = 5
   )
     bar
+
+quzzy = let (baz = 1) baz + 1
+
+// respect newlines in lets
+quzzzy =
+  let (baz = 1)
+    baz + 1