internal/rosa/package: migrate many libraries

This also adds more string helpers.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/package/libxml2.az

@@ -0,0 +1,23 @@
+package libxml2 {
+	description = "an XML toolkit implemented in C";
+	website = "https://gitlab.gnome.org/GNOME/libxml2";
+	anitya = 1783;
+
+	version* = "2.15.3";
+	source = remoteGitLab {
+		domain = "gitlab.gnome.org";
+		suffix = "GNOME/libxml2";
+		ref = "v"+version;
+		checksum = "oJy74htGlEpf70KPvpW18fYJo0RQQkCXZRwqUz6NoXborS3HCq3Nm4gsyaSeNmUH";
+	};
+
+	// can't create shell.out: Read-only file system
+	writable = true;
+
+	exec = meson {};
+
+	inputs = [
+		git,
+		diffutils,
+	];
+}