I was going to update the adding a new component docs, but while I was
reading them that the best way to simplify them would be to automate the
process.
* Added the `cargo start-bindings` tool.
* Removed the "Converting an existing Component to UniFFI" HOWTO. I
believe that all our existing components have been converted so
there's no need to keep updating this.
* Added a section about dependencies and the build.gradle file.
* Removed the `pub use` items from the megazord lib.rs files. I don't
believe they were needed.
Ben Dean-Kawamura