Simplicity versioning

[Sdoba16]

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Added functionality to parse versions from .simf file and download necessary binary file from SimplicityHL repo.

• Added parsing the version from the .simf file.
• Added parser of the floating version string and extractor of most appropriate version based on SimplicityHL releases.
• Added installed version check and version downloader from the SimplicityHL repo.
• Added compilers CLI command to return installed simplicity versions.