Allow pasting into fields in test UI

[mcintyre94]

I'm not 100% about this fix, I might be missing some nuance about how search bar items work

But the reason pasting was not working is because item.value ||= clipboardText was never updating, because item.value was truthy:

This PR changes it to always replace item.value with the pasted text

An alternative fix would be to remove the {current: true} from the Custom item, so that item.value is just whatever that field contains, but I'm not sure what that represents/would do.
Actually I guess that wouldn't work because then you couldn't paste unless the field was empty. I'm not sure if there are circumstances where we shouldn't change item.value on paste though.

Fixes #188

[acheroncrypto]

20a935c would override any existing text in the input. I think the problem is caused by the last commit that fixed the issue #187.

Specifically the line

solana-playground/client/src/components/SearchBar/SearchBar.tsx

Line 103 in 59d36a8

: props.value

We're setting the value to props.value which is an older value, in this case resets the input. I've changed it to use inputRef.current?.value ?? props.value. Let me know if this fixes it.

[mcintyre94]

Gotcha thanks, fix looks good! :)