Create an ECJ version of StrictJavaDepsPlugin

[guw]

Once #5 is available we need to create a plug-in that implements StrictJavaDepsPlugin based on the ECJ AST.

/**
 * A plugin for BlazeJavaCompiler that checks for types referenced directly in the source, but
 * included through transitive dependencies. To get this information, we hook into the type
 * attribution phase of the BlazeJavaCompiler (thus the overhead is another tree scan with the
 * classic visitor). The constructor takes a map from jar names to target names, only for the jars
 * that come from transitive dependencies (Blaze computes this information).
 */
public final class StrictJavaDepsPlugin extends BlazeJavaCompilerPlugin {..}

There might be a more efficient way to do this in ECJ without the need of #5.

[guw]

Fixed with #15 by configuring access rules and collecting dependency information separately