Initialization Code may exceed the 24576 byte limit for code

[HerbertJordan]

This issue was discovered and reported by @HonzaDajc:

While contracts stored in the chain are limited to 24576 bytes, code initialising a contract is unlimited in size. In particular, such a code may exceed 64k, and thus the limit of the 2-byte PC counter currently used by the LFVM. Such a case was encountered in the Ethereum mainnet history.

The Tosca VM implementations need to be adapted to be able to handle larger input codes.

[HerbertJordan]

Two proposals that have been proposed by @HonzaDajc on how to handle the problem:

• extend the LFVM format from a 2-byte instruction + 2-byte data to a 2-byte instruction + 4-byte data format to support the PC instruction which requires the 4-byte program counter as an immediate parameter
• introduce a rule in Fantom that init code may not exceed 64k