Format type annotation as part of the type, not part of the modifiers list

Given e.g. `@Deprecated @nullable Object foo() {}`, prefer this:

```
@deprecated
@nullable Object foo() {}
```

instead of:

```
@deprecated
@nullable
Object foo() {}
```

The implementation is complicated by the fact that the AST doesn't store
source position information for modifiers, and there's no requirement that
declaration annotations, modifiers, and type annotations appear in any
particular order in source.

To work around this, we examine the token stream to figure out the ordering
of the modifiers and annotations.

#5

PiperOrigin-RevId: 392459885

Author: cushon

core/pom.xml

@@ -51,7 +51,11 @@
       <artifactId>error_prone_annotations</artifactId>
       <optional>true</optional>
     </dependency>
-
+    <dependency>
+      <groupId>com.google.auto.value</groupId>
+      <artifactId>auto-value-annotations</artifactId>
+      <optional>true</optional>
+    </dependency>
 
     <!-- Test dependencies -->
     <dependency>

core/src/main/java/com/google/googlejavaformat/OpsBuilder.java

@@ -18,6 +18,8 @@
 import static java.lang.Math.min;
 
 import com.google.common.base.MoreObjects;
+import com.google.common.base.Preconditions;
+import com.google.common.base.Predicate;
 import com.google.common.collect.ArrayListMultimap;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
@@ -281,6 +283,28 @@ public final Optional<String> peekToken(int skip) {
         : Optional.empty();
   }
 
+  /**
+   * Returns the {@link Input.Tok}s starting at the current source position, which are satisfied by
+   * the given predicate.
+   */
+  public ImmutableList<Tok> peekTokens(int startPosition, Predicate<Input.Tok> predicate) {
+    ImmutableList<? extends Input.Token> tokens = input.getTokens();
+    Preconditions.checkState(
+        tokens.get(tokenI).getTok().getPosition() == startPosition,
+        "Expected the current token to be at position %s, found: %s",
+        startPosition,
+        tokens.get(tokenI));
+    ImmutableList.Builder<Tok> result = ImmutableList.builder();
+    for (int idx = tokenI; idx < tokens.size(); idx++) {
+      Tok tok = tokens.get(idx).getTok();
+      if (!predicate.apply(tok)) {
+        break;
+      }
+      result.add(tok);
+    }
+    return result.build();
+  }
+
   /**
    * Emit an optional token iff it exists on the input. This is used to emit tokens whose existence
    * has been lost in the AST.