internal/rosa/package: migrate many libraries

This also adds more string helpers.

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

internal/rosa/package/libpng.az

@@ -0,0 +1,27 @@
+package libpng {
+	description = "the official PNG reference library";
+	website = "https://www.libpng.org/pub/png/libpng.html";
+	anitya = 1705;
+
+	version* = "1.6.58";
+	source = remoteTar {
+		url = "https://downloads.sourceforge.net/project/libpng/libpng"+
+			join {
+				elems = slice {
+					elems = split {
+						s = version;
+						sep = ".";
+						n = 3;
+					};
+					end = 2;
+				};
+			}+"/"+version+"/libpng-"+version+".tar.gz";
+		checksum = "m_a5lROJH7vmF3cMjqwTUqURuQLhV1JQx2ySPzcN3VPdgDB9pG3UINsIx_mtkr-t";
+		compress = gzip;
+	};
+
+	exec = make {};
+
+	inputs = [ zlib ];
+	runtime = [ zlib ];
+}