feat: add event core api to runtime

[tac0turtle]

Description

Closes: #14690

Opening this pr to get initial feedback on the approach. If this is good then i can plumb it through baseapp

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[alexanderbez]

We should probably add a few simple test cases for this type.

[julienrbrt]

lgtm, changelog is somewhat... undescriptive.
linter is complaining as well.

[aaronc]

There should be some tests and runtime needs to provide this service to modules.

[tac0turtle]

There should be some tests and runtime needs to provide this service to modules.

where should the tests exist? runtime doesnt seem to have tests