Added Code Generation For Java (Unirest)

[AcousticDeveloper]

PR Description

This PR adds automated code generation for Java's Unirest library and also tests the generated code.

Related Issues

• Related Issue #135
• Closes #135

Checklist

• [x] I have gone through the contributing guide
• [x] I have updated my branch and synced it with project main branch before making this PR
• [x] I have run the tests (flutter test) and all tests are passing

Added/updated tests?

• [x] Yes, I have added and personally tested all the test cases and the generated code behaves as expected.

Instructions to run the generated code in local computer

• Install Apache Maven on your local system. You can alternatively use ./mvnw if you don't want to install maven on your local system or have version incompatibility issues.
• Create a Java project following the maven directory structure.
• Include Unirest as Maven dependency as mentioned in the documentation.
• Include the generated code as Main class in your maven project.
• Create a MANIFEST file for specifying the Main Class inside the project as mentioned in the Documentation.

• You can otherwise use <build> tag inside <project> tag inside your pom.xml file, as following

  <build>
      <plugins>
          <plugin>
              <groupId>org.apache.maven.plugins</groupId>
              <artifactId>maven-dependency-plugin</artifactId>
              <executions>
                  <execution>
                      <id>copy-dependencies</id>
                      <phase>prepare-package</phase>
                      <goals>
                          <goal>copy-dependencies</goal>
                      </goals>
                      <configuration>
                          <outputDirectory>
                              ${project.build.directory}/libs
                          </outputDirectory>
                      </configuration>
                  </execution>
              </executions>
          </plugin>
          <plugin>
              <!-- Build an executable JAR -->
              <groupId>org.apache.maven.plugins</groupId>
              <artifactId>maven-jar-plugin</artifactId>
  
              <configuration>
                  <archive>
                      <manifest>
                          <addClasspath>true</addClasspath>
                          <classpathPrefix>libs/</classpathPrefix>
                          <!-- here we specify that we want to use the main method within the App class -->
                          <mainClass>{{Fully qualified ClassName where main method is located}}</mainClass>
                      </manifest>
                  </archive>
              </configuration>
          </plugin>
          <plugin>
              <groupId>org.apache.maven.plugins</groupId>
              <artifactId>maven-compiler-plugin</artifactId>
              <configuration>
                  <source>17</source>
                  <target>17</target>
              </configuration>
          </plugin>
      </plugins>
  </build>

• Build the project using mvn clean compile package and then execute the jar file.

[AcousticDeveloper]

I have mentioned the local code testing setup in the pull request description @animator.

[animator]

Thanks for the PR.