refactor: prepare for use of non-trapping integrity trait

[erights]

closes: #XXXX
refs: endojs/endo#2679

Description

Does for agoric-sdk what endojs/endo#2679 does for endo

Prepare for anticipated introduction and use of the non-trapping integrity trait as explained at https://github.com/endojs/endo/blob/b12eb434b6672f0ceae41be55aac7f24c4562b7b/packages/ses/docs/preparing-for-stabilize.md

These preparations must work now, before these traits are introduced, and should continue to work after these traits are introduced and used.

Security Considerations

Some things that had been deeply frozen automatically by harden are now manually frozen by explicit calls to freeze. We need to review these carefully to ensure that nothing has inadvertently be left unfrozen as a result of the changes in this PR.

Some proxies will become unhardenable, but they will still be hardenable as of now, so mistaken hardenings will not be detected.

Scaling Considerations

For this PR by itself, none. Using the shim-based implementation of the non-trapping trait will have scaling consequences: endojs/endo#2675

Documentation Considerations

https://github.com/endojs/endo/blob/b12eb434b6672f0ceae41be55aac7f24c4562b7b/packages/ses/docs/preparing-for-stabilize.md will need to be reflected in developer docs.

Testing Considerations

Since this PR by itself should be a pure refactor with no observable changes, there is nothing to test at this stage. The testing burden will come with #10796 to see how adequate these preparations were.

Compatibility Considerations

The point. This changes to coding patterns that should be compat both with the current status quo and with #10796

Upgrade Considerations

As a pure refactor, none.

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[mhofman]

This made me realize a broader upgrade hazard which I've described in endojs/endo#2675 (review)

[mhofman]

The change in this file points to a potential future upgrade hazard. It means we cannot simply use the currently deployed code and re-run its transcript on top of a lockdown + liveslots (or an XS engine) that introduces non-trapping behavior. Such a "replay" is one of the option we're still keeping under consideration, especially for the bootstrap vat which cannot be upgraded.