* fix(glimmer): preserve path literal segments
This change fixes scenarios where an input handlebars file containing literal segments would be
reformatted to unwrap the literal segments, causing syntax errors in the resulting output. An
example of this is below:
```
<!-- wrong: input.funky<api!response -->
{{input.[funky<api!response]}}
<!-- wrong: input.this one has spaces -->
{{input.[this one has spaces]}}
```
This also handles a scenario where the input contained deprecated '/' delimited paths, ensuring
that those paths are not wrapped with brackets. This exists to prevent breaking an existing test
`sub-expressions.hbs`. Handling it this way does lead to some minor ambiguity since glimmer does
not support these paths, but the ambiguity is probably better than breaking them entirely.
fixes#14207, preventing removal of brackets where necessary
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Co-authored-by: fisker <lionkay@gmail.com>
fisker Cheung