Add mount path into the default generated openapi.json spec (#17839)

The current behaviour is to only add mount paths into the generated `opeanpi.json` spec if a `generic_mount_paths` flag is added to the request. This means that we would have to maintain two different `openapi.json` files, which is not ideal. The new solution in this PR is to add `{mount_path}` into every path with a default value specified:

```diff
--    "/auth/token/accessors/": {
++    "/auth/{mount_path}/accessors/": {
      "parameters": [
        {
          "name": "mount_path",
          "description": "....",
          "in": "path",
          "schema": {
            "type": "string",
++          "default": "token"
          }
        }
      ],
```

Additionally, fixed the logic to generate the `operationId` (used to generate method names in the code generated from OpenAPI spec). It had a bug where the ID had `mountPath` in it. The new ID will look like this:

```diff
-- "operationId": "listAuthMountpathAccessors",
++ "operationId": "listTokenAccessors",
```

sdk/framework/path.go

@@ -317,7 +317,7 @@ func (p *Path) helpCallback(b *Backend) OperationFunc {
 
 		// Build OpenAPI response for this path
 		doc := NewOASDocument()
-		if err := documentPath(p, b.SpecialPaths(), requestResponsePrefix, false, b.BackendType, doc); err != nil {
+		if err := documentPath(p, b.SpecialPaths(), requestResponsePrefix, b.BackendType, doc); err != nil {
 			b.Logger().Warn("error generating OpenAPI", "error", err)
 		}