Add support for JSON assertions using JSON compare

This commit moves JSON content AssertJ support from Spring Boot.

See gh-21178

Co-authored-by: Brian Clozel <brian.clozel@broadcom.com>

spring-test/src/test/resources/org/springframework/test/json/different.json

@@ -0,0 +1,6 @@
+{
+  "gnirps": [
+    "boot",
+    "framework"
+  ]
+}

spring-test/src/test/resources/org/springframework/test/json/example.json

@@ -0,0 +1,4 @@
+{
+  "name": "Spring",
+  "age": 123
+}

spring-test/src/test/resources/org/springframework/test/json/lenient-same.json

@@ -0,0 +1,6 @@
+{
+  "spring": [
+    "framework",
+    "boot"
+  ]
+}

spring-test/src/test/resources/org/springframework/test/json/nulls.json

@@ -0,0 +1,4 @@
+{
+  "valuename": "spring",
+  "nullname": null
+}

spring-test/src/test/resources/org/springframework/test/json/simpsons.json

@@ -0,0 +1,36 @@
+{
+  "familyMembers": [
+    {
+      "name": "Homer"
+    },
+    {
+      "name": "Marge"
+    },
+    {
+      "name": "Bart"
+    },
+    {
+      "name": "Lisa"
+    },
+    {
+      "name": "Maggie"
+    }
+  ],
+  "indexedFamilyMembers": {
+    "father": {
+      "name": "Homer"
+    },
+    "mother": {
+      "name": "Marge"
+    },
+    "son": {
+      "name": "Bart"
+    },
+    "daughter": {
+      "name": "Lisa"
+    },
+    "baby": {
+      "name": "Maggie"
+    }
+  }
+}

spring-test/src/test/resources/org/springframework/test/json/source.json

@@ -0,0 +1,6 @@
+{
+  "spring": [
+    "boot",
+    "framework"
+  ]
+}

spring-test/src/test/resources/org/springframework/test/json/types.json

@@ -0,0 +1,18 @@
+{
+  "str": "foo",
+  "num": 5,
+  "pi": 3.1415926,
+  "bool": true,
+  "arr": [
+    42
+  ],
+  "colorMap": {
+    "red": "rojo"
+  },
+  "whitespace": "    ",
+  "emptyString": "",
+  "emptyArray": [
+  ],
+  "emptyMap": {
+  }
+}