regressions_SUITE will have code snippets which previously crashed the compiler.

This commits includes a test for Maps crash in beam_bool.

* bjorn/compiler/spurious-warning:
  sys_core_fold: Eliminate warnings for unused terms in effect context
  sys_core_fold: Eliminate warnings for unused terms

The optimization introduced in 0a0d39d351fc could cause spurious
warnings of the type: "a term is constructed, but never used".
That would happen for constructs in effect context.

To avoid those warnings, we will need to apply warning suppression
also in effect context.

The optimization introduced in 0a0d39d351fc would cause spurious
warnings of the type: "a term is constructed, but never used".

To avoid the warning, we must mark not only tuples and lists as
compiler_generated, but also each element. We must also propagate
compiler_generated annotations in lets. For example, if we have:

  let <X -| ['compiler_generated']> = 42 in X + 1

we must propagate the compiler_generated annotation to the literal
when do constant propagation:

  42 -| ['compiler_generated'] + 1

* nox/compiler/parse_transform-undef/OTP-12723:
  Properly report unknown parse transforms

Simplify the uniq/0 function by using erlang:unique_integer/1.