Fixes memory leak in the React editor

[ncordon]

This was reproducible when making the web repl grow gradually. For example by copy pasting the same example query back to back:

MATCH (n:Person)
WHERE n.name = "Steve" 
RETURN n 
LIMIT 12;

The memory consumption in Firefox jumped from 25 MiB to 400 MiB, I have even seen GiB if you keep on writing queries.

After the change:

Why

I don't have a clear idea yet why this was happening, but I suspect we are holding the old string in the onChange, so we are just preventing the GC from cleaning old values of the editor?

[OskarDamkjaer]

If you only remove the ...props does that fix in by itself? or are both changes needed

[ncordon]

After discussing we think we'll have to solve this in a different way. Removing the setState from the onChange appears to prevent the tree visualization, as we don't update the variable that holds the new query when we modify the editor text.

@OskarDamkjaer has also proved you can have memory leaks by just pressing and unpressing the dark mode button several times. The leaks are likely coming from the react-codemirror library, so we'll try replacing that part