feature: support for Parameter.content (#5571)

* add `getParameterSchema` OAS helper

* use `Parameter.content.[firstKey].schema` as schema value when present

* `newValue` -> `initialValue`

* make `paramWithMeta` a const

* add trailing comma to `swagger2SchemaKeys`

* refactor `helpers` to a folder

* deprecate `src/core/utils.js` in favor of `src/core/helpers/`

* support `Parameter.content.[mediaType].schema` in validateParam

* reject `null` as an OAS3 object value

* expose Fetch errors in the browser console

* generate ParameterRow default values based on `content` values

* add tests for `getParameterSchema`

* remove debugger statement

* remove debugger statement

* don't apply `generatedSampleValue`s to parameters with `examples`

* remove extra semi

* disable JSON check in parameter runtime validation

* stringify JsonSchema_object textarea values

* add Cypress tests

* swagger-client@3.9.4

test/e2e-cypress/tests/bugs/4442.js

@@ -0,0 +1,37 @@
+/**
+ * @prettier
+ */
+
+describe("UI #4442: Parameter.content display and execution", function() {
+  it("should display textareas as static documentation according to the `example`", () => {
+    cy.visit("/?url=/documents/bugs/4442.yaml")
+      .get(`#operations-default-get_`)
+      .click()
+      .get(".btn.try-out__btn")
+      .click()
+      .get(
+        `div.json-schema-array > div:nth-child(1) > div > textarea`
+      )
+      .should("have.value", `{\n  "userId": 1,\n  "currency": "USD"\n}`)
+      .get(
+        `div.json-schema-array > div:nth-child(2) > div > textarea`
+      )
+      .should("have.value", `{\n  "userId": 2,\n  "currency": "CAD"\n}`)
+  })
+  it("should serialize JSON into a query correctly", () => {
+    cy.visit("/?url=/documents/bugs/4442.yaml")
+      .get(`#operations-default-get_`)
+      .click()
+      .get(".btn.try-out__btn")
+      .click()
+      .get(".btn.execute")
+      .click()
+      .get(".request-url pre")
+      .should(
+        "have.text",
+        `http://localhost:3230/?users=${encodeURIComponent(
+          `[{"userId":1,"currency":"USD"},{"userId":2,"currency":"CAD"}]`
+        )}`
+      )
+  })
+})