Search code for TODOs and add appropriate issues

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> This resolves the following FIXME by incorporating the functionality added to BLT in [LLNL/blt#436](https://github.com/LLNL/blt/pull/436):
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> https://github.com/LLNL/serac/blob/4dbb20800e4914ccfb5b42903f65f589cb03b610/examples/using-with-cmake/CMakeLists.txt#L7-L10
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> Fixes #470
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> Possibly this would have been noticed earlier if we had opened a GitHub issue instead of just leaving it as a TODO?

Yeah, I try to catch this stuff and add issues as I see them, but I know we have some hanging out in the code base. We should probably do a search to grab all the TODO items.

_Originally posted by @jamiebramwell in https://github.com/LLNL/serac/issues/472#issuecomment-848129857_

Search the repository for TODO and FIXME markers, including the CMakeLists.txt location referenced in the issue, and review each item in context. Create an appropriate GitHub issue for every actionable item, recording enough context and a clear scope; done means the relevant TODOs have been identified and tracked.

Written by the indexing model from the issue text.