Fix GSP formatting

As reported by customer ([forum thread](http://www.jetbrains.net/devnet/message/5263276)):

current GSP formatting algorithm behaves at the following manner:

**Before**
```

@import url("${resource(dir: 'styles', file: 'base.css')}");
@import url("${resource(dir: 'styles', file: 'tabs.css')}");
@import url("${resource(dir: 'styles', file: 'navigation.css')}");
@import url("${resource(dir: 'styles', file: 'splitter.css')}");
<g:if test="${pageProperty(name: 'body.class') == 'administration'}">
@import url("${resource(dir: 'styles', file: 'administration.css')}");
</g:if>

```
**After**
```

@import url("${resource(dir: 'styles', file: 'base.css')}");
@import url("${resource(dir: 'styles', file: 'tabs.css')}");
@import url("${resource(dir: 'styles', file: 'navigation.css')}");
@import url("${resource(dir: 'styles', file: 'splitter.css')}");
<
g:if

test
=
"
${
pageProperty(name: 'body.class') == 'administration'
}
"
>
@import url("${resource(dir: 'styles', file: 'administration.css')}");

</
g:if
>

```
The task is to fix GSP formatting algorithm

---

*Imported from [IDEA-54974](https://youtrack.jetbrains.com/issue/IDEA-54974) · Type: Bug · Votes: 0*
*Comments, attachments, dates and reporter are not part of the export — follow the link above for the full history.*

Start by locating the GSP formatting algorithm in the plugin and compare its output with the issue's Before and After examples. Reproduce the formatting of the embedded g:if tag, then verify that tag attributes and the surrounding HTML and CSS remain intact.

Written by the indexing model from the issue text.