Rename SystemMetrics to SystemInfo

There are more pieces of information about a system than just its CPU,
Memory and disk metrics.  To avoid having to build a separate collection
and subscription for metrics and system info, rename the existing system
metrics to system info in anticipation of providing additonal static
system information such as CPU model in it.

test/lib/data/SystemInfo.js

@@ -0,0 +1,22 @@
+"use strict";
+const assert = require("assert").strict;
+
+const lib = require("@clusterio/lib");
+const { SystemInfo } = lib;
+
+
+describe("lib/data/ModPack", function() {
+	describe("class SystemInfo", function() {
+		it("correctly calculates derived metrics", function() {
+			const system = new SystemInfo("controller", [0.5, 0.25, 0, 1], 1024, 768, 2048, 512, 0, false);
+			assert.equal(system.cpuCapacity, 4);
+			assert.equal(system.cpuUsed, 1.75);
+			assert.equal(system.cpuAvailable, 2.25);
+			assert.equal(system.cpuRatio, 0.4375);
+			assert.equal(system.memoryUsed, 256);
+			assert.equal(system.memoryRatio, 0.25);
+			assert.equal(system.diskUsed, 1536);
+			assert.equal(system.diskRatio, 0.75);
+		});
+	});
+});

test/lib/data/SystemMetrics.js

@@ -1,22 +0,0 @@
-"use strict";
-const assert = require("assert").strict;
-
-const lib = require("@clusterio/lib");
-const { SystemMetrics } = lib;
-
-
-describe("lib/data/ModPack", function() {
-	describe("class SystemMetrics", function() {
-		it("correctly calculates derived metrics", function() {
-			const metrics = new SystemMetrics("controller", [0.5, 0.25, 0, 1], 1024, 768, 2048, 512, 0, false);
-			assert.equal(metrics.cpuCapacity, 4);
-			assert.equal(metrics.cpuUsed, 1.75);
-			assert.equal(metrics.cpuAvailable, 2.25);
-			assert.equal(metrics.cpuRatio, 0.4375);
-			assert.equal(metrics.memoryUsed, 256);
-			assert.equal(metrics.memoryRatio, 0.25);
-			assert.equal(metrics.diskUsed, 1536);
-			assert.equal(metrics.diskRatio, 0.75);
-		});
-	});
-});