pegs.nim now compiles with strictFuncs

[nc-x]

Closes #18057
Closes #16892

The issue here is that with strictFuncs, if we are calling a function inside a noSideEffect function, then that called function must also be marked as noSideEffect. (I have never used noSideEffect/strictFuncs before so idk whether this is expected behaviour or not.)
This PR converts few procs to funcs so that pegs.nim compiles properly.

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This PR also updates all noSideEffect procs in pegs.nim to use func instead.
The changes for this are in a separate commit for easy review.

[konsumlamm]

The issue here is that with strictFuncs, if we are calling a function inside a noSideEffect function, then that called function must also be marked as noSideEffect. I am not sure whether this is expected behaviour or not.

That is intended, that's exactly the point of func/noSideEffect (even without strictFuncs).

[nc-x]

func/noSideEffects/strictFuncs need better error messages, so that they list out where the side effects come from. Going through a huge file looking for side effects is pretty annoying, and take out any advantage that they could provide.

[timotheecour]

func/noSideEffects/strictFuncs need better error messages, so that they list out where the side effects come from

PR welcome

some of the changes in this PR were useful ({. noSideEffect.} => func)

other than that, I consider the current design for strictFuncs+views broken (#16305) so that's what should be fixed instead, not stdlib (there are better alternatives as discussed elsewhere)

[quantimnot]

@nc-x Why was this closed?
I would like to be able to use strictFunc globally for some of my projects that use the pegs module.