prefer-array-find rule autofixer could singularize variable name

[bmish]

The autofixer for prefer-array-find could be updated to singularize the variable name since the variable now refers to a single item instead of an array in the following situation.

Before:

const calls = calls.filter((call) => call.isFoo);
assert.ok(calls[0].isBar);

After autofix (current):

const calls = calls.find((call) => call.isFoo);
assert.ok(calls.isBar);

After autofix (desired):

const call = calls.find((call) => call.isFoo);
assert.ok(call.isBar);

This fix would be similar to the singularization performed in the no-for-loop rule as a result of #745.

[fisker]

I did metion this variable rename in the original proposal.

The name may confuse people const allTrueArray = array.filter(foo) -> const allTrueArray = array.find(foo) the allTrueArray is not an array anymore.

#730 (comment)

I forgot why I didn't consider rename it, but I remember there is a good reason maybe not.

[fisker]

PR welcome.

[bmish]

I have opened a fix in #1243.