Implement low_level_call into the multisig

[K1-R1]

Type of change

• New feature

Changes

The following changes have been made:

• transfer and execute_transaction have been merged into a single function: execute_transaction
• SRC-2 has been implemented
• A single hash function compute_hash has replaced the separate hash functions.
• The use of arbitrary bytes in hash functions has been removed, more detail available in notes below.
• pub(crate)

Notes

• Arbitrary bytes in hash functions have been removed as they served to add additional entropy; however this is not necessary as knowing the hash does not create a vulnerability, the hash must still be signed over by a multisig user.
• The test functions::info::compute_hash::gets_call_hash has been written, but is ignored with the following reason:

Encoding of nested structs with Bytes fields in the RustSDK doesn't match the encoding in Sway. This is not an issue for the use of compute_hash when making a contract call; as the user would not be creating the hash in the SDK

Related Issues

Closes #22
Closes #717
Closes #718

Implementing SRC-2 Closes #424

[K1-R1]

Comments addressed, @Braqzen

[Braqzen]

Niceu, almosto thereo my friendo