Pact should not allow the usage of REPL natives in module code

[CryptoPascal31]

Pact legacy was disallowing by default REPL natives in module code.
Preventing developers testing modules that finally aren't deployable on chain.

Pact legacy was providing the convenient API (env-enable-repl-natives ) to however enable them for special cases.

Pact core always allows the usage of REPL natives in module code. IMO, it should not.

Since Pact core enables writing top-level functions, I'm not sure that (env-enable-repl-natives ) is still useful.

I suggest the following:

• Always disable REPL natives in module context
• But enable REPL natives in top-level functions (and ofc in top-level directly)
• Do not implement (env-enable-repl-natives ) in Pact core

[jmcardon]

Since Pact core enables writing top-level functions, I'm not sure that (env-enable-repl-natives ) is still useful.

Top-level functions are repl-only. This is purely for convenience. I can disable them in .pact files in the future. They should only be enabled in .repl files.

Always disable REPL natives in module context

I'm ok with making it opt-in like prod. I've already used repl natives numerous times to debug contracts within pact-5 so I don't think I want to remove this capability.

I think we can implement env-enable-repl-natives with relative ease. I was already doing so in a separate branch, but work got halted for more important issues. We'll look into it again