Add Create & Update Token Commands to Stake-Pool CLI

[sense112]

Adding the following commands to the spl-stake-pool rust cli:

• create_token_metadata
• update_token_metadata

All arguments have been catered for with friendly descriptions.

[joncinque]

Thanks so much for your contribution! There's just two small things to fixup.

Also, in order to pass CI, the code has to be formatted per rustfmt, so could you run ./cargo-nightly fmt --all from the root of the repo and commit the change?

And finally, I don't think this will be an issue, but to be safe, can you also make sure this passes clippy? You can run that from the root of the repo with:

$ ./cargo-nightly clippy -Zunstable-options --all-targets --features test-sbf -- --deny=warnings --deny=clippy::arithmetic_side_effects

Once that's all done, this should be good to merge!

[sense112]

Took me some time to get my environment setup correctly to run these commands.

Thanks for the comments! I have run the format command and clippy seems happy :)

[joncinque]

Great job, thanks for your contribution!