treewide: add meta.mainProgram to packages with a single binary

The nixpkgs-unstable channel's programs.sqlite was used to identify
packages producing exactly one binary, and these automatically added
to their package definitions wherever possible.

pkgs/development/tools/java/java-language-server/default.nix

@@ -53,6 +53,7 @@ maven.buildMavenPackage rec {
 
   meta = with lib; {
     description = "A Java language server based on v3.0 of the protocol and implemented using the Java compiler API";
+    mainProgram = "java-language-server";
     homepage = "https://github.com/georgewfraser/java-language-server";
     license = licenses.mit;
     maintainers = with maintainers; [ hqurve ];