docs: docs and tests for case insensitive like operator (#6281)

* Add doc + tests for case insensitive like operator

* added postgres check since its a postgres-specific

Co-authored-by: Umed Khudoiberdiev <pleerock.me@gmail.com>

docs/find-options.md

@@ -268,6 +268,22 @@ will execute following query:
 SELECT * FROM "post" WHERE "title" LIKE '%out #%'
 ```
 
+* `ILike`
+
+```ts
+import {ILike} from "typeorm";
+
+const loadedPosts = await connection.getRepository(Post).find({
+    title: ILike("%out #%")
+});
+```
+
+will execute following query:
+
+```sql
+SELECT * FROM "post" WHERE "title" ILIKE '%out #%'
+```
+
 * `Between`
 
 ```ts

docs/zh_CN/find-options.md

@@ -261,6 +261,22 @@ const loadedPosts = await connection.getRepository(Post).find({
 SELECT * FROM "post" WHERE "title" LIKE '%out #%'
 ```
 
+-   `ILike`
+
+```ts
+import { ILike } from "typeorm";
+
+const loadedPosts = await connection.getRepository(Post).find({
+    title: ILike("%out #%")
+});
+```
+
+将执行以下查询：
+
+```sql
+SELECT * FROM "post" WHERE "title" ILIKE '%out #%'
+```
+
 -   `Between`
 
 ```ts

src/find-options/operator/ILike.ts

@@ -2,7 +2,7 @@ import {FindOperator} from "../FindOperator";
 
 /**
  * Find Options Operator.
- * Example: { someField: ILike("%some sting%") }
+ * Example: { someField: ILike("%SOME string%") }
  */
 export function ILike<T>(value: T|FindOperator<T>) {
     return new FindOperator("ilike", value);

test/functional/repository/find-options-operators/repository-find-operators.ts

@@ -6,6 +6,7 @@ import {
     Connection,
     Equal,
     If,
+    ILike,
     In,
     IsNull,
     LessThan,
@@ -518,6 +519,50 @@ describe("repository > find options > operators", () => {
 
     })));
 
+    it("ilike", () => Promise.all(connections.map(async connection => {
+        if (!(connection.driver instanceof PostgresDriver))
+            return;
+
+        // insert some fake data
+        const post1 = new Post();
+        post1.title = "about #1";
+        post1.likes = 12;
+        await connection.manager.save(post1);
+        const post2 = new Post();
+        post2.title = "ABOUT #2";
+        post2.likes = 3;
+        await connection.manager.save(post2);
+
+        // check operator
+        const loadedPosts = await connection.getRepository(Post).find({
+            title: ILike("%out #%")
+        });
+        loadedPosts.should.be.eql([{ id: 1, likes: 12, title: "about #1" }, { id: 2, likes: 3, title: "ABOUT #2" }]);
+
+    })));
+
+    it("not(ilike)", () => Promise.all(connections.map(async connection => {
+        if (!(connection.driver instanceof PostgresDriver))
+            return;
+
+        // insert some fake data
+        const post1 = new Post();
+        post1.title = "about #1";
+        post1.likes = 12;
+        await connection.manager.save(post1);
+        const post2 = new Post();
+        post2.title = "ABOUT #2";
+        post2.likes = 3;
+        await connection.manager.save(post2);
+
+        // check operator
+        const loadedPosts = await connection.getRepository(Post).find({
+            title: Not(ILike("%out #1"))
+        });
+        loadedPosts.should.be.eql([{ id: 2, likes: 3, title: "ABOUT #2" }]);
+
+    })));
+
     it("between", () => Promise.all(connections.map(async connection => {
 
         // insert some fake data