Use self-CPI for logging

[samuelvanderwaal]

This PR changes the program to use the Anchor event_cpi feature for logging instead of the normal Solana logs which can get truncated by the validator.

The two additional accounts caused stack overflow issues in the mip1-sol-fulfill-buy accounts struct, so to fix this:

• the superfluous rent account was removed
• some address constraint checks were moved from the accounts struct to inside the handler logic

The removal of the rent account is a breaking change and required the client to be updated and any code consuming the client will need to be updated to no longer pass in the rent account.

Program logs before change:

Program logs after change:

Self-cpi:

[nothing0012]

we might have some indexing depends on this logging

[samuelvanderwaal]

Yes, that's correct. The idea behind this PR is to change the way logging happens to avoid truncated logs causing misses on indexing, but it requires updating the indexing parser to handle the new logging method. So the indexing changes should be implemented before this PR is merged. @madergaser knows what needs to happen on this.