Getting Started Script (#4879)

closes https://github.com/paritytech/polkadot-sdk/pull/4879

Provide a fast and easy way for people to get started developing with
Polkadot SDK.

Sets up a development environment (including Rust) and clones and builds
the minimal template.

Polkadot address: 16xyKzix34WZ4um8C3xzMdjKhrAQe9DjCf4KxuHsmTjdcEd

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Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>
Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>