feat!: provide constructor functions for expectations

[haraldmaida]

When composing custom expectations using the expectations combinators (not, all, any) it should be possible to construct the expectations in a convenient and readable form. Therefore we should provide constructor functions for expectations, e.g.

instead of :

let custom_expectation = all((not(IsZero), IsAtLeast { expected: -40 }, IsAtMost { expected: 100 }));

we can write:

let custom_expectation = all((not(is_zero()), is_at_least(-40), is_at_most(100)));

Implemented a constructor function for each of the provided expectations.

BREAKING CHANGES:

• the existing constructor functions new of the expectation structs have been marked as deprecated and will be removed in some later release.

[codecov]

Codecov Report

Attention: Patch coverage is 98.80000% with 6 lines in your changes missing coverage. Please review.

Project coverage is 93.84%. Comparing base (9119cda) to head (2b28758).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/expectations.rs	98.34%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #55      +/-   ##
==========================================
- Coverage   96.30%   93.84%   -2.47%     
==========================================
  Files          32       32              
  Lines        4227     4546     +319     
  Branches     4227     4546     +319     
==========================================
+ Hits         4071     4266     +195     
- Misses        110      234     +124     
  Partials       46       46              

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