feat: add castResult function

[aleclarson]

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Summary

Add a castResult function for coercing an (error, value) pair into a Result tuple (introduced by #132).

• The CastResult type is used in the castResult function's return type.
• Type tests are included (it was hard to cover all the edge cases!)

Related issue, if any:

Merge #132 first!

For any code change,

• Related documentation has been updated, if needed
• Related tests have been added or updated, if needed
• Related benchmarks have been added or updated, if needed

Does this PR introduce a breaking change?

No

Bundle impact

Status	File	Size	Difference (%)
M	src/async/defer.ts	686 1	+259 (+60%)
M	src/async/parallel.ts	1493	+259 (+20%)
M	src/async/tryit.ts	502	+259 (+106%)
A	src/function/castResult.ts	409	+409
A	src/typed/isResult.ts	193	+193

Footnotes

1. Function size includes the import dependencies of the function. ↩

[aleclarson]

Closing this. The use cases are too limited, I think, and it adds unnecessary bloat to the other functions I tried using it in. I considered splitting the promise-handling into a new castResultPromise function, but then both castResult and castResultPromise started to look too much like syntax sugar.

That said, I'll be refactoring the types of tryit to use the new Result types introduced in #132.