Language does not get passed for user actions when using CustomButton

[ivarne]

Description of the bug

doPerformAction wants a language parameter

app-frontend-react/src/queries/queries.ts

Lines 146 to 155 in f60c181

	export const doPerformAction = async (
	partyId: string,
	dataGuid: string,
	data: unknown,
	language?: string,
	): Promise<ActionResult> => {
	const response = await httpPost(getActionsUrl(partyId, dataGuid, language), undefined, data);
	if (response.status !== 200) {
	throw new Error('Failed to perform action');
	}

But it is not set in CustomButtonComponent

app-frontend-react/src/layout/CustomButton/CustomButtonComponent.tsx

Lines 165 to 166 in f60c181

	return doPerformAction(partyId, instanceGuid, { action: action.id, buttonId });
	},

Steps To Reproduce

1. Create an app with a custom button that triggers an IUserAction that read UserActionContext.Language property
2. Click the button and see that the property is null.

Additional Information

This issue replaces Altinn/app-lib-dotnet#927