feat: Update types for Cypress.Chainable.task to allow for parameterizing the task return type (#8753)

Co-authored-by: Zach Bloomquist <github@chary.us>

cli/types/cypress.d.ts

@@ -1766,7 +1766,7 @@ declare namespace Cypress {
      *
      * @see https://on.cypress.io/task
      */
-    task(event: string, arg?: any, options?: Partial<Loggable & Timeoutable>): Chainable<Subject>
+    task<S = unknown>(event: string, arg?: any, options?: Partial<Loggable & Timeoutable>): Chainable<S>
 
     /**
      * Enables you to work with the subject yielded from the previous command.

cli/types/tests/cypress-tests.ts

@@ -608,3 +608,15 @@ namespace CypressShadowTests {
   .get('.foo')
   .find('.bar', {includeShadowDom: true})
 }
+
+namespace CypressTaskTests {
+  cy.task<number>('foo') // $ExpectType Chainable<number>
+  cy.task<number>('foo').then((val) => {
+    val // $ExpectType number
+  })
+
+  cy.task('foo') // $ExpectType Chainable<unknown>
+  cy.task('foo').then((val) => {
+    val // $ExpectType unknown
+  })
+}