method chain breaking heuristic (#6685)

* examples from various issues about method chaining

this commit includes no prettier functionality changes, so that diffs will be easily visible.

specifically:

* https://github.com/prettier/prettier/issues/4125
* https://github.com/prettier/prettier/pull/4765
* https://github.com/prettier/prettier/issues/1565
* https://github.com/prettier/prettier/issues/3107

* add heuristic for breaking method chains

* fix: remove unnecessary escape characters

* initial non-regex isSimple implementation

* handle babel literal types properly

found here: https://github.com/babel/babel/blob/fe258dec047f473fb5a35172b2ff8cb172051dec/packages/babel-parser/ast/spec.md

* template literal + test

* use !every instead of some(!)

* fix: some test cases

* fix: object expressions and some more simple node types

* some test cases showing need for depth check

* depth check

* update test to test thing it's supposed to test

* optional expressions

* test case for missing isSimple depth

* fix isSimple depth bug

* fix: comment check

* test for ts non-null operator

* make object properties behave similarly to arrays

* isSimple -> isSimpleCallArgument; move to utils; add unaries

* add Import to the list of simple things

* only short regexps to be considered simple (<= 5 chars)

* add changelog entry in the new format

* update snapshots

Co-authored-by: Georgii Dolzhykov <thorn.mailbox@gmail.com>

changelog_unreleased/javascript/pr-6685.md

@@ -0,0 +1,22 @@
+#### Method chain breaking ([#6685](https://github.com/prettier/prettier/pull/6685) by [@mmkal](https://github.com/mmkal))
+
+Previously, any chained method calls of length three or longer would be automatically broken. This uses a heuristic for the complexity of the arguments in the chain, rather than just the chain length. Now, if chained method calls have arguments which aren't easy to understand at a glance (e.g. functions or deeply-nested objects), the chain is broken. Otherwise, they're allowed to remain on one line. See prior issues [#3197](https://github.com/prettier/prettier/issues/3107), [#4765](https://github.com/prettier/prettier/pull/4765), [#1565](https://github.com/prettier/prettier/issues/1565) and [#4125](https://github.com/prettier/prettier/pull/4125) for context and examples.
+
+<!-- prettier-ignore -->
+```javascript
+// Input
+foo.one().two().three() === bar.four().five().six();
+
+// Output (Prettier stable)
+foo
+  .one()
+  .two()
+  .three() ===
+  bar
+    .four()
+    .five()
+    .six();
+
+// Output (Prettier master)
+foo.one().two().three() === bar.four().five().six();
+```