feat: add support for 64-bit registry access in key_access enum

[EricS (ESiebigteroth)]

This PR extends the key_access enum in registry_helpers.h to support 64-bit registry access. The following new values have been added:

• read64: Opens a key for reading from the 64-bit registry.
• readwrite64: Opens a key for reading and writing from the 64-bit registry.

Additionally, the get_access_flags function has been updated to handle these new enum values appropriately.

[EricS (ESiebigteroth)]

#435 has a similar problem.

[Antanas Uršulis (aursulis)]

As a drive-by since I was looking into whether WIL does this or not, could we add the KEY_WOW64_32KEY variants as well, assuming Microsoft would take this PR?

[Duncan Horn (dunhor)]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[EricS (ESiebigteroth)]

Thanks Duncan Horn (@dunhor) and Chris Guzak (@ChrisGuzak) for reviewing and approving the changes! I really appreciate your time.
Let me know if there's anything else needed before merging.

[Duncan Horn (dunhor)]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[Duncan Horn (dunhor)]

@microsoft-github-policy-service rerun

[Duncan Horn (dunhor)]

@microsoft-github-policy-service rerun

[Duncan Horn (dunhor)]

Thanks Duncan Horn (@dunhor) and Chris Guzak (@ChrisGuzak) for reviewing and approving the changes! I really appreciate your time. Let me know if there's anything else needed before merging.

LGTM. I'm just not sure what's going on with the CLA bot. I wonder if it's somehow related to the outages yesterday. I'll try kicking it again later to see if it's resolved.

[Duncan Horn (dunhor)]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[Duncan Horn (dunhor)]

Looks like I can't complete because I was the last to push... Chris Guzak (@ChrisGuzak), if you don't mind can you re-approve