Workspace dependencies

[4meta5]

Closes #44 by defining all dependencies once in a workspace Cargo.toml.

This improves developer experience for dependency upgrades in 2 ways:

1. After this change, dependencies only need to be updated in one file (workspace Cargo.toml) instead of requiring the exact same changes to every Cargo.toml which contains the dependency.
2. This ensures the same version of the same dependency are used within this workspace to ensure and enforce compatibility between the provided template node/runtime/pallet.

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[ozgunozerk]

can you inform us on why this part is removed, and why it was not necessary?

[4meta5]

The build.rs file is intended to compile the runtime in wasm. This code was preventing the correct compilation so I changed it to match every other runtime build.rs I've seen.

I've never seen this in any other substrate project. In the future, I'd suggest PRing the polkadot-sdk build.rs file before making changes like this in the future to get feedback and confirmation that it works as intended.

[ozgunozerk]

https://github.com/paritytech/polkadot-sdk/blob/master/cumulus/parachain-template/runtime/build.rs

in case there was a misunderstanding, we didn't make any changes. This is from substrate

[ozgunozerk]

Looking good to me.

I have two questions above, but they are not blocking for this PR