feat(label): add several label props

[mlmoravek]

Closes #544

Proposed Changes

I added a label property to some components to makes the use of oruga more consistent.

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[codecov]

Codecov Report

Patch coverage: 33.33% and project coverage change: -0.08% ⚠️

Comparison is base (ef46040) 62.81% compared to head (17606dd) 62.74%.
Report is 2 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #582      +/-   ##
===========================================
- Coverage    62.81%   62.74%   -0.08%     
===========================================
  Files           79       79              
  Lines         5532     5529       -3     
  Branches      1532     1526       -6     
===========================================
- Hits          3475     3469       -6     
- Misses        1946     1949       +3     
  Partials       111      111              

Flag	Coverage Δ
oruga	65.92% <ø> (ø)
oruga-next	48.35% <33.33%> (-0.46%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
...-next/src/components/autocomplete/Autocomplete.vue	51.63% <0.00%> (-0.71%)	⬇️
...es/oruga-next/src/components/checkbox/Checkbox.vue	76.19% <50.00%> (-13.29%)	⬇️
...ckages/oruga-next/src/components/button/Button.vue	70.27% <100.00%> (ø)

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