Rename uniffi_bindgen crate to wp_uniffi_bindgen and update uniffi to 0.27.0

[oguzkocer]

We have the following warning when we run cargo doc:

warning: output filename collision.
The lib target uniffi_bindgen in package uniffi_bindgen v0.26.1 has the same output filename as the bin target uniffi_bindgen in package uniffi_bindgen v0.1.0 (./wordpress-rs/uniffi_bindgen).
Colliding filename is: ./wordpress-rs/target/doc/uniffi_bindgen/index.html
The targets should have unique names.
This is a known bug where multiple crates with the same name use
the same path; see rust-lang/cargo#6313.

In order to address that, I've renamed our crate to wp_uniffi_bindgen and updated the Makefile and the Gradle config accordingly.

While making the changes, I noticed that uniffi had a new release, so I updated it to 0.27.0 which required a few minor updates in the Android project. Also, there was a breaking change in project's trunk related to authentication token, so I've updated that in Android as well.