This commit attempts to improve testing of strictFuncs and views, and
prevent regressions like #16873 (resolved by 0b01eddace).
We previously only explicitly tested strictFuncs and views with a
smaller number of stdlib modules, mostly in:
- tests/effects/tstrict_funcs.nim
- tests/views/tcan_compile_nim.nim
Note that this commit leaves the `pegs` module commented out; it
cannot currently be compiled with `--experimental:views` (see #16892).
Note also that this commit is not sufficient to test strictFuncs and
views, but it does detect a subset of problems.
Previously, compiling a file containing just `import critbits` with
`nim c --experimental:strictFuncs` would produce the following error:
critbits.nim(529, 6) Error: 'toCritBitTree' can have side effects
This was introduced by 2aed418698 (#16564).
Fixes: #16873