Add EJML dependency to wpiutil (#1769)

Add EJML as the Java library for linear algebra for use in wpilib. This is equivalent to Eigen for C++.

The EJML dependency is downloaded in cmake and pulled in via maven in the gradle build.

docs/build.gradle

@@ -97,6 +97,7 @@ ext {
 apply from: "${rootDir}/shared/opencv.gradle"
 
 task generateJavaDocs(type: Javadoc) {
+    classpath += project(":wpiutil").sourceSets.main.compileClasspath
     options.links("https://docs.oracle.com/en/java/javase/11/docs/api/")
     options.addStringOption "tag", "pre:a:Pre-Condition"
     options.addStringOption('Xdoclint:accessibility,html,missing,reference,syntax')