Remove v0 encoding logic

[danielbate]

Once #2050 has been merged and sway encoding improvements to v1 have been completed, we should remove all v0 specific logic:

• Encoding should now fallback to v1, strategy can remain in place for future custom encoding
• Remove redundant v0 coders, some redistribution may be required for anything still being used by transactions
• Remove v0 function selector encoding and contract call script
• Remove heap pointer logic
• Remove heap type validation for multicalls
• Remove experimental tests
• Ensure documentation type support is up to date

[arboleya]

@danielbate I think we can start this right after #2050, regardless of FuelLabs/sway#5727.

Only v1 will be accepted anyway, and the stabilization should be transparent.

[danielbate]

Agreed 👍🏻