Fix comparison in BaseHtml::renderSelectOptions()

[WinterSilence]

Current behavior of BaseHtml::renderSelectOptions() is incorrect:

• multiple selection: method always converts $selection and $key to strings
• single selection: method compare $selection and $key as strings at strict comparation
• error at non-strict comparation integer/float($key) with object($selection)

As result, in some cases method return invalid value or throw error.

I'm created 2 PR's:

1. Fixes comparison completly in BaseHtml::renderSelectOptions() #19577 Complete, but breaks BC
2. Fix error at not-stict comparison in BaseHtml::renderSelectOptions() #19579 Fix only error at non-stict comparation

[papppeter]

string keys would be perfect for me!