Allow small letters to match capital letters

[FranklinYu]

Is your feature request related to a problem? Please describe.

Assume history like

grep StringBuilder main.java
grep int main.java

I want to use this line when I only typed

grep s

Currently I have to type

grep S

in order to reject the more recent grep int entry (note the capital letter S).

Describe the solution you'd like

After I typed s, I want the text tringBuilder main.java be suggested; when I hit the right arrow to apply the suggestion, I want the s (that I typed) to be converted to S in addition. This is similar to Zsh completion configuration

zstyle ':completion:*' matcher-list 'm:{a-z}={A-Za-z}'

Describe alternatives you've considered

current behavior

Additional context

N/A