APIServer: Add support for filtering to list rpc (#1175)

This is not intended to be used to support `--filter` or similar on the
CLIs list yet, it's solely to clean up our rather awkward use of
`ContainerClient.list()` today in the CLI. The list RPC simply returns
all of the containers we have created. Because of this, for a LOT of our
commands we filter to what we need client side, which feels like a
waste.. This change introduces a filter struct that we can provide an
array of container IDs, labels, and the status of the containers to
filter the `list()` output from.

This additionally, because it was killing (pun not intended) me and I
was already having to change this area for the `list()` additions,
changes container kill slightly to return an error if you try and kill a
container that doesn't exist.

Sources/ContainerCommands/System/SystemStop.swift

@@ -79,9 +79,8 @@ extension Application {
                 log.info("waiting for containers to exit")
                 do {
                     for _ in 0..<Self.shutdownTimeoutSeconds {
-                        let anyRunning = try await client.list()
-                            .contains { $0.status == .running }
-                        guard anyRunning else {
+                        let runningContainers = try await client.list(filters: ContainerListFilters(status: .running))
+                        guard !runningContainers.isEmpty else {
                             break
                         }
                         try await Task.sleep(for: .seconds(1))