fix(common): fix @endo/common integration breakage

[erights]

closes: #XXXX
refs: #1935

Description

#1935 broke the agoric-sdk integration tests, i.e., would have broke integration with agoric-sdk . To repair the problem, this PR

• gets rid of the index.js file which rolled up all the exports together
• moves each of the source files -- each of which currently represents a separately exported utility -- to the top level.
• changes the corresponding "exports": to use the same export name as the source file it exports, so that imports are the same whether processed by a tool that understands "exports": or not.
• change all importers to do the deep import of the particular exports it needs.

Security Considerations

none

Scaling Considerations

By forcing importers to import only from the exporting file they need, some implementations (bundlers, packagers) can do tree-shaking, omitting code not reachable from imports. For @endo/common specifically, the savings are tiny. But the pattern could bring substantial savings elsewhere.

Documentation Considerations

nothing interesting

Testing Considerations

none

Upgrade Considerations

The old exports prior to #1935 that were exporting some of these, for compat, still reexports these. But it deprecates those reexports, with advice that importers do a deep import directly from @endo/common/.... Thus, this PR should not have any compat issues compared to the state preceding #1935.

This PR is technically a compat break with #1935 itself. But #1935 was just merged and never released, so that is not a source of worry.

[kriskowal]

That covers it. It might or might not save time to propose a no-op PR to agoric-sdk pinned to this branch to verify that CI settles.

[erights]

That covers it. It might or might not save time to propose a no-op PR to agoric-sdk pinned to this branch to verify that CI settles.

Agoric/agoric-sdk#7937

[erights]

For the record, Agoric/agoric-sdk#7937 CI is currently green with #endo-branch: markm-fix-common-package, so merging. Afterwards, I'll switch Agoric/agoric-sdk#7937 back to master.