Enforce braces around conditionals

Wanted to get thoughts on prettier enforcing braces around conditionals (example below). I believe prettier-js has shot down this request in the past on the grounds that they don't want to modify the AST, but I'm not sure if prettier-java has already crossed that bridge. It would probably be a controversial decision and is maybe a slippery slope, but I think it's pretty well-established at this point that using braces around conditionals is a best practice for correctness and maintainability, so I think it would be reasonable for prettier-java to enforce it.

**Prettier-Java 1.0.2*

```sh
# Options (if any):
--print-width 80
```

**Input:**

```java
public class Test {

public void method() {
if (true) System.out.println("hi");
}
}
```

**Output:**

```java
public class Test {

public void method() {
if (true) System.out.println("hi");
}
}
```

**Expected behavior:**

```java
public class Test {

public void method() {
if (true) {
System.out.println("hi");
}
}
}
```

Start by reproducing the Java input with Prettier-Java 1.0.2 and compare the current output with the expected braced form in this issue. Investigate how conditional statements are represented and formatted, then determine the scope of enforcing braces consistently. Done means the example formats with braces and related conditional cases are covered by tests.

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