This commit updates the Gradle wrapper to version 6.5.1 to address some
of the issues we were having when importing the project.

This change merges the four main OpenDC development repositories into a
single Git repository and performs final organization of the repository.

This change prepares the simulator Git repository for the monorepo residing at
https://github.com/atlarge-research.com/opendc. To accomodate for this, we
move all files into a simulator subdirectory.

This change prepares the opendc repository for a monorepo setup by
moving all files to the core/ directory. After all repositories have
been merged into this repository, we will move the correct files back.

This change adds a workaround for the Windows build where Gradle fails
to compile the Kotlin code in `buildSrc` due to CRLF line endings.

See https://github.com/gradle/gradle/issues/12248

This change ensures that the batch file for invoking the Gradle wrapper
is treated as a file with Windows line endings.