Complete implementation of SessionStorage retrieval in FDC3 for the Web implementation

[kriswest]

The implementation of Session Storage retrieval and the constraining of methods of re-connecting to the desktop agent is not fully implemented in the FDC3 for the Web project. If stored data is found for the specified appId, then discovery methods should be limited to the previous type used (from the 4 defined, see https://deploy-preview-1191--fdc3.netlify.app/docs/next/api/ref/GetAgent#persisted-connection-data). E.g. if the FAILOVER type was found, the failover function should be run immediately, whereas if PROXY_URL is found, with an agentUrl set, then an iframe should be injected with that URL etc..

Handling of the stored data can be found at:

FDC3/packages/fdc3-get-agent/src/messaging/AbstractWebMessaging.ts

Lines 52 to 63 in 13425af

	retrieveInstanceUuid(): string | undefined {
	const detailsStr = globalThis.sessionStorage.getItem(this.sessionKey())
	if (detailsStr) {
	const details = JSON.parse(detailsStr) as DesktopAgentDetails
	if (details.agentType == WebDesktopAgentType.ProxyParent) {
	return details.instanceUuid
	}
	}
	return undefined;
	}

It is currently limited to retrieval of an instanceUuid in 1 of the 4 cases and is not affecting discovery as specified.

The final implementation will also be affected by #1430 which will need to change the structure of the data stored.