Add tryFromString method

[markinigor]

Description

Add tryFromString method that

Motivation and context

It is usefull with deserialization json with optional|nullable uuid parameters.
And it similar to BackedEnum::tryFrom function, but with nullable param
https://www.php.net/manual/ru/backedenum.tryfrom.php

How has this been tested?

Copied tests from existing fromString testcase. Added test for null, empty string and invalid string

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

PR checklist

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING.md document.
• I have added tests to cover my changes.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.65%. Comparing base (d459bdb) to head (a1ad7e9).
Report is 42 commits behind head on 4.x.

Additional details and impacted files

@@             Coverage Diff              @@
##                4.x     #557      +/-   ##
============================================
+ Coverage     95.64%   95.65%   +0.01%     
- Complexity      583      587       +4     
============================================
  Files            70       70              
  Lines          1560     1566       +6     
============================================
+ Hits           1492     1498       +6     
  Misses           68       68              

Files with missing lines	Coverage Δ
src/Uuid.php	98.13% <100.00%> (+0.11%)	⬆️

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