fix fv str-to-int

[rsoeldner]

This PR fixes the order of parameters (in case base is defined) to match documentation https://pact-language.readthedocs.io/en/latest/pact-properties-api.html?highlight=str-to-int#str-to-int.
Additionally, we re-organize str-to-int str and str-to-int base str to be close to each other.
I've added a property test case for both cases.

fixed #1303

PR checklist:

• Test coverage for the proposed changes
• PR description contains example output from repl interaction or a snippet from unit test output
• Documentation has been updated if new natives or FV properties have been added. To generate new documentation, issue cabal run tests. If they pass locally, docs are generated.
• Any changes that could be relevant to users have been recorded in the changelog
• In case of changes to the Pact trace output (pact -t), make sure pact-lsp is in sync.

Additionally, please justify why you should or should not do the following:

• Confirm replay/back compat
• Benchmark regressions
• (For Kadena engineers) Run integration-tests against a Chainweb built with this version of Pact

[imalsogreg]

This looks great to me!