Move Poseidon sage script

[SupremoUGH]

Changes:

• Sage script generate_parameters_grain_deterministic.sage moved from archived repo Plonk-Prototype to manta-rs.
• Slightly modified generate_parameters_grain_deterministic_sage so it outputs the round constants for ark-ff in the desired format.
• Added text file lfsr_values with the relevant part of the outputs.
• Modified grain_lfsr_is_consistent in round_constants.rs so it checks every round constant and not just the first two.

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Closes #84

Before we can merge this PR, please make sure that all the following items have been checked off:

• Linked to an issue with discussion and accepted design OR have an explanation in the PR that describes this work.
• Added one line describing your change in CHANGELOG.md and added the appropriate changelog label to the PR.
• Re-reviewed Files changed in the GitHub PR explorer.
• Checked that changes and commits conform to the standards outlined in CONTRIBUTING.md.
• Ran cargo hakari generate to update the workspace-hack system

[bhgomes]

Also, please update the Poseidon README.md.