Docs: adding first version of the auto-generated packages API docs. (#22107)

* trying out api-extractor.

* works with our setup of build.

* wip.

* changed the packages so it works better with the api-extractor.

* Changes to make the api-extractor to work.

* cleaned up the api-extractor config files.

* added some more documentation.

* added tsdoc-metadata to gitignore.

* removed the generated docs (will do that in another PR).

* added execute permission to script for generating dosc.

* added so we will push generated docs to branch.

* will clean packages_api on abort.

* Fixed failing tests.

* fixed formatting issue with typedoc comment.

* temporarily disabled tslint rules about namespace until https://github.com/microsoft/rushstack/issues/1029 is resolved

* temporary enabled bable namespaces.

* updated build script.

* updated script.

* updated script with some colors.

* changed to camelCase.

* removed spacing.

* Starting to add documentation guidelines.

* added examples headline.

* added menu options.

* added parameters and return values.

* Fixed merge error.

* Added first version of auto-generated docs.

* changed so we use the eslint ignore syntax.

* changed to correct eslint ingnore comment.

* fixed some spelling errors reported by codespell.

* added script to generate docs in current folder.

* updated api docs.

* lerna bootstrap.

* added eror to the ingore words list.

* removed file that should be ignored.

* updated locKFILE.

* referenced the code comments guidelines.

* updated packages.

* updated deps.

* updated the autogenerated dosc.

* adding missing new line.

docs/sources/packages_api/runtime/backendsrv.md

@@ -0,0 +1,158 @@
++++
+# -----------------------------------------------------------------------
+# Do not edit this file. It is automatically generated by API Documenter.
+# -----------------------------------------------------------------------
+title = "BackendSrv"
+keywords = ["grafana","documentation","sdk","@grafana/runtime"]
+type = "docs"
+draft = true
++++
+
+## BackendSrv interface
+
+<b>Signature</b>
+
+```typescript
+export interface BackendSrv 
+```
+<b>Import</b>
+
+```typescript
+import { BackendSrv } from '@grafana/runtime';
+```
+<b>Methods</b>
+
+|  Method | Description |
+|  --- | --- |
+|  [datasourceRequest(options)](#datasourcerequest-method) |  |
+|  [delete(url)](#delete-method) |  |
+|  [get(url, params, requestId)](#get-method) |  |
+|  [patch(url, data)](#patch-method) |  |
+|  [post(url, data)](#post-method) |  |
+|  [put(url, data)](#put-method) |  |
+|  [request(options)](#request-method) |  |
+
+### datasourceRequest method
+
+<b>Signature</b>
+
+```typescript
+datasourceRequest(options: BackendSrvRequest): Promise<any>;
+```
+<b>Parameters</b>
+
+|  Parameter | Type | Description |
+|  --- | --- | --- |
+|  options | <code>BackendSrvRequest</code> |  |
+
+<b>Returns:</b>
+
+`Promise<any>`
+
+### delete method
+
+<b>Signature</b>
+
+```typescript
+delete(url: string): Promise<any>;
+```
+<b>Parameters</b>
+
+|  Parameter | Type | Description |
+|  --- | --- | --- |
+|  url | <code>string</code> |  |
+
+<b>Returns:</b>
+
+`Promise<any>`
+
+### get method
+
+<b>Signature</b>
+
+```typescript
+get(url: string, params?: any, requestId?: string): Promise<any>;
+```
+<b>Parameters</b>
+
+|  Parameter | Type | Description |
+|  --- | --- | --- |
+|  url | <code>string</code> |  |
+|  params | <code>any</code> |  |
+|  requestId | <code>string</code> |  |
+
+<b>Returns:</b>
+
+`Promise<any>`
+
+### patch method
+
+<b>Signature</b>
+
+```typescript
+patch(url: string, data?: any): Promise<any>;
+```
+<b>Parameters</b>
+
+|  Parameter | Type | Description |
+|  --- | --- | --- |
+|  url | <code>string</code> |  |
+|  data | <code>any</code> |  |
+
+<b>Returns:</b>
+
+`Promise<any>`
+
+### post method
+
+<b>Signature</b>
+
+```typescript
+post(url: string, data?: any): Promise<any>;
+```
+<b>Parameters</b>
+
+|  Parameter | Type | Description |
+|  --- | --- | --- |
+|  url | <code>string</code> |  |
+|  data | <code>any</code> |  |
+
+<b>Returns:</b>
+
+`Promise<any>`
+
+### put method
+
+<b>Signature</b>
+
+```typescript
+put(url: string, data?: any): Promise<any>;
+```
+<b>Parameters</b>
+
+|  Parameter | Type | Description |
+|  --- | --- | --- |
+|  url | <code>string</code> |  |
+|  data | <code>any</code> |  |
+
+<b>Returns:</b>
+
+`Promise<any>`
+
+### request method
+
+<b>Signature</b>
+
+```typescript
+request(options: BackendSrvRequest): Promise<any>;
+```
+<b>Parameters</b>
+
+|  Parameter | Type | Description |
+|  --- | --- | --- |
+|  options | <code>BackendSrvRequest</code> |  |
+
+<b>Returns:</b>
+
+`Promise<any>`
+