refactor: improve the std API

[moul]

• Rename std.Get* -> std.*.
• Return Frame struct{Addr,PkgPath} instead of string for std.Caller*.

Addresses #683

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• Added new tests, or not needed, or not feasible
• Provided an example (e.g. screenshot) to aid review or the PR is self-explanatory
• Updated the official documentation or not needed
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• Provided any useful hints for running manual tests

Maintainers Checklist

• Checked that the author followed the guidelines in CONTRIBUTING.md
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[thehowl]

@moul what's the state on this? Are we holding it off awaiting decision / further discussion on Frames?

I think it might be good to merge std.Get* -> std.* in the meantime (I very much agree on that change) and maybe hold off frames management as per #683 ?

[moul]

Yeah, let’s split into two PRs; feel free to continue my work, else I will work on it soon.

[thehowl]

Let's continue on #2425