Enhancement: Extract FieldDefinition\Value

[localheinz]

This PR

• extracts FieldDefinition\Value

Follows #157.

[codecov]

Codecov Report

Merging #160 into master will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##             master     #160      +/-   ##
============================================
+ Coverage     98.20%   98.23%   +0.02%     
- Complexity       79       81       +2     
============================================
  Files            15       16       +1     
  Lines           223      226       +3     
============================================
+ Hits            219      222       +3     
  Misses            4        4              

Impacted Files	Coverage Δ	Complexity Δ
src/FieldDefinition.php	100.00% <100.00%> (ø)	9.00 <1.00> (ø)
src/FieldDefinition/Value.php	100.00% <100.00%> (ø)	2.00 <2.00> (?)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 743f4b4...8772f6e. Read the comment docs.