OAPI: add option to make a job setting auto-evaluatable by the user

Add a new job setting option `autoevalLockable`. Setting this to `true` in
the job compiler's `JOB_TYPE` settings has the following effect:

- By default, the setting will not be editable in Blender's job submission
  interface. Instead, a toggle button with a 'car' icon will be shown.
- When the 'car' button is toggled off, the setting becomes editable again.

In its default, uneditable state, the setting will be auto-evaluated before
submission.

This makes it possible to 'lock in' auto-evaluation. The main use case is
for the frame range of the render job. By default this will be locked to
the scene frame range, but it can still be overridden if a different
range is wanted.

This commit just contains the necessary OpenAPI change.

pkg/api/flamenco-openapi.yaml

@@ -1683,6 +1683,20 @@ components:
         "eval":
           type: string
           description: Python expression to be evaluated in order to determine the default value for this setting.
+        "autoevalLockable":
+          # This setting uses camelCase, as 'autoeval_lockable' would translate
+          # to an 'AutoevalLockable' property in the Go code, which should be
+          # accessed as 'autoevalLockable' in the job compiler JavaScript file.
+          # To keep things consistent, the property is just named
+          # `autoevalLockable` here too.
+          type: boolean
+          default: false
+          description: >
+            Enables a toggle option in the submission interface to enable
+            auto-evaluation. When toggled on, the `eval` setting will always be
+            evaluated on job submission. An example use is the to-be-rendered
+            frame range, which by default automatically follows the scene range,
+            but can be overridden manually when desired.
         "visible":
           $ref: "#/components/schemas/AvailableJobSettingVisibility"
         "required":