Add loader-v4 instruction constructors

[pgarg66]

Problem

Need convenient methods to construct loader-v4 instructions. These will be useful in CLI and other places.

Summary of Changes

Add the constructors.

Fixes #

[dmakarov]

LGTM. I assume there will be some tests that will use these methods?

[pgarg66]

LGTM. I assume there will be some tests that will use these methods?

Yes, need to add some tests. I looked into bpf_loader_upgradeable.rs for some inspiration, but those tests are not as useful. loader-v4/src/lib.rs is another place where the tests could potentially be added.

[dmakarov]

LGTM. I assume there will be some tests that will use these methods?

Yes, need to add some tests. I looked into bpf_loader_upgradeable.rs for some inspiration, but those tests are not as useful. loader-v4/src/lib.rs is another place where the tests could potentially be added.

Sounds good. I thought maybe in some tests that construct instructions directly, these methods could be used, if that's convenient.

[pgarg66]

LGTM. I assume there will be some tests that will use these methods?

Yes, need to add some tests. I looked into bpf_loader_upgradeable.rs for some inspiration, but those tests are not as useful. loader-v4/src/lib.rs is another place where the tests could potentially be added.

Sounds good. I thought maybe in some tests that construct instructions directly, these methods could be used, if that's convenient.

Yes, those should be simpler to add. Let me try and add it in this PR. I would also like to add some tests that calls the loader with the constructed instructions. Maybe that can go in a separate PR.

[pgarg66]

Added tests for the constructors.

[dmakarov]

LGTM.

[Lichtso]

recipient_address is not needed and should be payer_address here as well.

[pgarg66]

I thought about it. The caller can pass the payer address as the recipient_address.