Dependency extraction webpack plugin: Change option name consistent with docs

[sirreal]

Description

In the docs, an option name was provided as requestToHandle, but the
actual option in use was requestToDependency.

Update the code and related tests to use requestToHandle as described
in the documentation instead of requestToDependency.

How has this been tested?

The test suite is updated to use the updated option name without regressions.

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.

[sirreal]

The relevant test for this functionality:

gutenberg/packages/dependency-extraction-webpack-plugin/test/fixtures/overrides/webpack.config.js

Lines 15 to 19 in a5b0cbc

	requestToHandle( request ) {
	if ( request === 'rxjs' || request === 'rxjs/operators' ) {
	return 'wp-script-handle-for-rxjs';
	}
	},

And its snapshot (unchanged since master):

gutenberg/packages/dependency-extraction-webpack-plugin/test/__snapshots__/build.js.snap

Lines 40 to 88 in a5b0cbc

	exports[`Webpack \`overrides\` should produce expected output: Dependencies JSON should match snapshot 1`] = `
	Array [
	"wp-blob",
	"wp-script-handle-for-rxjs",
	"wp-url",
	]
	`;
	exports[`Webpack \`overrides\` should produce expected output: External modules should match snapshot 1`] = `
	Array [
	Object {
	"externalType": "this",
	"request": Object {
	"this": Array [
	"wp",
	"blob",
	],
	},
	"userRequest": "@wordpress/blob",
	},
	Object {
	"externalType": "this",
	"request": Object {
	"this": Array [
	"wp",
	"url",
	],
	},
	"userRequest": "@wordpress/url",
	},
	Object {
	"externalType": "this",
	"request": Object {
	"this": Array [
	"rxjs",
	"operators",
	],
	},
	"userRequest": "rxjs/operators",
	},
	Object {
	"externalType": "this",
	"request": Object {
	"this": "rxjs",
	},
	"userRequest": "rxjs",
	},
	]
	`;

[gziolo]

Yes, it makes sense to update 👍 It wasn't published to npm so it should be good to land without any notes.