feat: docs plugin options sidebarCollapsible + sidebarCollapsed (#5203)

* Add prop

Signed-off-by: Josh-Cena <sidachen2003@gmail.com>

* Add `collapsible` option to sidebar item

Signed-off-by: Josh-Cena <sidachen2003@gmail.com>

* Add eslint-ignore

Signed-off-by: Josh-Cena <sidachen2003@gmail.com>

* Move new page

Signed-off-by: Josh-Cena <sidachen2003@gmail.com>

* Allow in autogenerated

Signed-off-by: Josh-Cena <sidachen2003@gmail.com>

* Fix tests

Signed-off-by: Josh-Cena <sidachen2003@gmail.com>

* Move config options to plugin-docs

Signed-off-by: Josh-Cena <sidachen2003@gmail.com>

* Make non-collapsible items always expanded

Signed-off-by: Josh-Cena <sidachen2003@gmail.com>

* docs versioning cli should receive a single options object

* Update cli.test.ts

* revert validateCategoryMetadataFile change

* remove theme usage of themeConfig.sidebarCollapsible

* better handling of sidebar item category inconsistencies + add warning message

* Update snapshot

Signed-off-by: Josh-Cena <sidachen2003@gmail.com>

* Handle plugin option inconsistencies

* improve doc for new sidebarCollapsible doc options

* remove warning in fixSidebarItemInconsistencies as it will be annoyed for versioned sites, as "collapsed" is already persisted in sidebar json files

Co-authored-by: slorber <lorber.sebastien@gmail.com>

website/_dogfooding/docs-tests-sidebars.js

@@ -12,6 +12,12 @@ module.exports = {
       id: 'index',
       label: 'Index',
     },
+    {
+      type: 'category',
+      label: 'section',
+      collapsible: false,
+      items: ['index', 'more-test'],
+    },
     {
       type: 'category',
       label: 'Huge sidebar category',