feat(4.6): Allow mutating field array iterable's value property

[logaretm]

What

This PR implements an enhancement for the FieldArray or useFieldArray where it wasn't possible to use v-model with it to mutate the iterable value directly.

The motivation for that design is to force the lib user to go through the API, however, it doesn't seem necessary to have this restriction as v-model is an initiative way to mutate such values.

This was mentioned in #3617 discussion

[codecov-commenter]

Codecov Report

Merging #3618 (8ca61e3) into v4.6 (f48f348) will increase coverage by 0.22%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             v4.6    #3618      +/-   ##
==========================================
+ Coverage   96.34%   96.57%   +0.22%     
==========================================
  Files          68       68              
  Lines        1834     1840       +6     
  Branches      457      458       +1     
==========================================
+ Hits         1767     1777      +10     
+ Misses         67       63       -4     

Impacted Files	Coverage Δ
packages/vee-validate/src/useFieldArray.ts	94.11% <100.00%> (+3.85%)	⬆️

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