Update interface of revertibleRandom

[darkdrag00nv2]

Work towards #2712

For previous discussions, please check - #2943

Description

1. Introduced a new type FixedSizeUnsignedInteger
2. Update the interface of the revertibleRandom function to fun revertibleRandom<T: FixedSizeUnsignedInteger>([modulo: T]): T

Note that updating the interface is a breaking change as the existing usage of the function such as below fails.

let rand1 = revertibleRandom()  // error: cannot infer type parameter: `T`

Noteworthy Points

1. Updating the interface is a breaking change as pointed out in the description and also the issue Update revertibleRandom interface (FLIP 120) #2712 (comment)
2. Since we don't support type inference of function arguments, we will run into the same issues as the InclusiveRange constructor function: Fix incorrect type inference for InclusiveRange #2886

Basically:

let r = revertibleRandom<Int8>(0) // checker error, type mismatch - expected: Int8, Found - Int
let r = revertibleRandom<Int8>(Int8(0)) // success

3. The modulo operation hasn't been implemented in this PR. It'll be done in a future PR based on the discussion on the issue.

---

• Targeted PR against master branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work
• Code follows the standards mentioned here
• Updated relevant documentation
• Re-reviewed Files changed in the Github PR explorer
• Added appropriate labels

[codecov]

Codecov Report

Attention: 5 lines in your changes are missing coverage. Please review.

Comparison is base (0de878b) 80.12% compared to head (901bb55) 80.15%.

Files	Patch %	Lines
runtime/stdlib/random.go	95.90%	4 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2976      +/-   ##
==========================================
+ Coverage   80.12%   80.15%   +0.02%     
==========================================
  Files         348      348              
  Lines       81796    81925     +129     
==========================================
+ Hits        65537    65663     +126     
- Misses      13939    13942       +3     
  Partials     2320     2320              

Flag	Coverage Δ
unittests	80.15% <96.55%> (+0.02%)	⬆️

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[turbolent]

Great work!