Initialize UniFFI demo and scripts

[swaptr]

• Initializes the base for building and testing uniffi demo application.
• Added convenience scripts for setting up and compiling uniffi_aries_vcx project for android.

[swaptr]

@gmulhearn While building the bindings using the uniffi_aries_vcx/scripts/android.build.sh, on generating the kotlin bindings, i run into the following error:

error: linking with `cc` failed: exit status: 1

...

error: could not compile `ursa` (lib) due to previous error
warning: build failed, waiting for other jobs to finish...

For reference, I have set up the toolchain using scripts inside the uniffi_aries_vcx/scripts directory.

[codecov-commenter]

Codecov Report

Merging #896 (b84c65d) into main (72744e1) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #896   +/-   ##
=======================================
  Coverage   44.44%   44.45%           
=======================================
  Files         417      417           
  Lines       28975    28975           
  Branches     6176     6176           
=======================================
+ Hits        12879    12880    +1     
+ Misses      12297    12296    -1     
  Partials     3799     3799           

Flag	Coverage Δ
unittests-aries-vcx	44.45% <ø> (+<0.01%)	⬆️

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see 1 file with indirect coverage changes

[gmulhearn]

As discussed, the solution may be:

1. unset some of the compile env variables OPENSSL_DIR etc. as they may be interfering with the cargo run of uniffi-bindgen, or
2. move the uniffi-bindgen step to somewhere BEFORE the setting of environment variables and building for android architectures

[swaptr]

1. `unset` some of the compile env variables `OPENSSL_DIR` etc. as they may be interfering with the `cargo run` of uniffi-bindgen, or

You are absolutely correct @gmulhearn. This fixed it right away. Thanks.

[gmulhearn]

LGTM! nice work. As we know, this is all in a WIP state, but it's a good base for the next PRs to pull everything together.

nice work. no need to address the comment i left in this PR, we will handle it in the next PR

[Patrik-Stas]

Cool!

Just one thing, can you add brief instructions for the build steps and running in android? For starter doesn't need to be super detailed, but to give me idea how to proceed if I want to try it out.
Also mention the current state of support - what architectures are supporter, or whether the builds work emulator / physical device.

@gmulhearn feel free to merge at your discretion