Add assertions to generic transfer and update docs

[joshuahannan]

Closes: #162

Description

• Adds assertions to generic_transfer_with_address to make sure the vault is the correct type
• Added a test with MaliciousToken to test the transaction. MaliciousToken is the same as ExampleToken, but returns the ExampleToken paths in the FTVaultData view instead of its own paths.
• Adds FLIX to the main generic transactions
• Updates comments in FungibleToken
• Updates tests to use the pre-deployed versions of the contracts that do not come from this repo instead of deploying new ones

I can't think of any other assertions to put in the transactions, but I am open to suggestions

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For contributor use:

• Targeted PR against master branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code follows the standards mentioned here.
• Updated relevant documentation
• Re-reviewed Files changed in the Github PR explorer
• Added appropriate labels