feat(core): add identity function

[griest024]

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• The commit message follows our guidelines: https://github.com/graycoreio/daffodil/blob/develop/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
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PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Other... Please describe:

What is the new behavior?

While this might seem useless, its nice to have a single function that will be used for places where transforms are required by type but no transform logic is needed (will happen for injectable actions). This prevents multiple identity functions being created (as they would if defined inline, though possibly closured out) which should improve memory usage.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information