fix/Lookup Autocomplete fixes

[ibelar]

Various fix for Lookup and Autocomplete field

Fixes #656, #663, #664

• Keep previous select value;
• Proper width apply when used in group;
• Remove empty filter label

[codecov]

Codecov Report

Merging #671 into develop will increase coverage by 0.01%.
The diff coverage is 100%.

@@              Coverage Diff              @@
##             develop     #671      +/-   ##
=============================================
+ Coverage      72.74%   72.76%   +0.01%     
  Complexity      1869     1869              
=============================================
  Files            102      102              
  Lines           4418     4421       +3     
=============================================
+ Hits            3214     3217       +3     
  Misses          1204     1204

Impacted Files	Coverage Δ	Complexity Δ
src/FormField/AutoComplete.php	65.95% <100%> (+0.36%)	33 <0> (ø)	⬇️
src/FormField/Lookup.php	76.79% <100%> (+0.25%)	55 <0> (ø)	⬇️

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[FabulousGee]

Fix for #656 confirmed.

[DarkSide666]

looks good, thanks!