Add new Client API

Signed-off-by: Helder Correia <174525+helderco@users.noreply.github.com>

tests/plan/client/filesystem/read/fs/usage/test.cue

@@ -0,0 +1,27 @@
+package main
+
+import (
+	"dagger.io/dagger"
+)
+
+dagger.#Plan & {
+	client: filesystem: rootfs: read: {
+		contents: dagger.#FS
+		exclude: ["*.log"]
+	}
+	actions: test: {
+		[string]: dagger.#ReadFile & {
+			input: client.filesystem.rootfs.read.contents
+		}
+		valid: {
+			path:     "test.txt"
+			contents: "local directory"
+		}
+		conflictingValues: {
+			path:     "test.txt"
+			contents: "local foobar"
+		}
+		excluded: path:  "test.log"
+		notExists: path: "test.json"
+	}
+}