fix: stop hard-coding default guidebook

This PR allows client plugins to specify the default guidebook in config.d/client "defaultGuidebook", e.g.

```
{
  "defaultGuidebook": "ml/codeflare"
}
```

Author: starpit

Diff for: plugins/plugin-client-default/config.d/client.json

@@ -1,3 +1,4 @@
 {
+  "defaultGuidebook": "ml/codeflare",
   "contextRoot": ""
 }

Diff for: plugins/plugin-madwizard/src/plugin.ts

@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+import { defaultGuidebook } from "@kui-shell/client/config.d/client.json"
 import { Arguments, ParsedOptions, ReactResponse, Registrar, Tab } from "@kui-shell/core"
 
 export interface Options extends ParsedOptions {
@@ -104,7 +105,7 @@ export function doMadwizard({ readonlyUI = true, task, withFilepath = true, cb,
   return async ({ tab, argvNoOptions, parsedOptions }: Arguments<Options>) => {
     if (withFilepath && !argvNoOptions[1]) {
       // TODO codeflare should not be in plugin-madwizard
-      argvNoOptions.push(process.env.GUIDEBOOK || "ml/codeflare")
+      argvNoOptions.push(process.env.GUIDEBOOK || defaultGuidebook)
     }
 
     if (envFn) {