String concatenation formatting

**Prettier-Java 1.6.1**

Related to https://github.com/jhipster/prettier-java/issues/77.
In this case we're getting compilable code, it's just sub-ideal.

```sh
# Options (if any):
--print-width 140
```

**Input:**
```java
PreparedStatement statement =
connection.prepareStatement(
"INSERT INTO noneofyourbusiness(" +
"field1," +
"field2," +
"field3," +
"field4) " +
"VALUES (?, ?, ?, ?)");
```

**Output:**

```java
PreparedStatement statement = connection.prepareStatement(
"INSERT INTO noneofyourbusiness(" + "field1," + "field2," + "field3," + "field4) " + "VALUES (?, ?, ?, ?)"
);
```

**Expected behavior:**
I see two options:
- do not join the lines if they contain string concatenation like this
- join, but make sure to get rid of all the concatenation

Start with the Input, Output, and Expected behavior examples in this issue, then locate the formatter entry point that handles Java string concatenation. Reproduce the case with print width 140 and make the output follow one of the two proposed behaviors: preserve the concatenated lines or remove the concatenation. Verify the resulting formatting against the example.

Scritto dal modello di indicizzazione a partire dal testo della issue.