Ability to change "Create & Add Another"-button label

[Joorren]

In resources, you are able to change the label of the "Create :resource" and "Update :resource" buttons by overriding the createButtonLabel() and updateButtonLabel() methods respectively, but you aren't able to change the label of the "Create & Add Another" and "Update & Continue Editing" buttons. These values are hardcoded (only translatable) in the vue components.

It would be useful to have new methods provided for these buttons, e.g.:

    /**
     * Get the text for the create & add another resource button.
     *
     * @return string|null
     */
    public static function createAndAddAnotherButtonLabel()
    {
        return Nova::__('Create & Add Another');
    }

    /**
     * Get the text for the update & continue editing resource button.
     *
     * @return string|null
     */
    public static function updateAndContinueEditingButtonLabel()
    {
        return Nova::__('Update & Continue Editing');
    }

        <LoadingButton
          v-if="shouldShowAddAnotherButton"
          dusk="create-and-add-another-button"
          type="button"
          @click="submitViaCreateResourceAndAddAnother"
          :disabled="isWorking"
          :loading="wasSubmittedViaCreateResourceAndAddAnother"
        >
          {{ createAndAddAnotherButtonLabel }}
        </LoadingButton>

        <LoadingButton
          dusk="update-and-continue-editing-button"
          type="button"
          @click="submitViaUpdateResourceAndContinueEditing"
          :disabled="isWorking"
          align="center"
          :processing="wasSubmittedViaUpdateResourceAndContinueEditing"
        >
          {{ updateAndContinueEditingButtonLabel }}
        </LoadingButton>