gems: add solargraph gem

Add the Solargraph gem to enable Ruby language integration for
supporting text editors.

This enables various features, including code completion, inline
documentation, type checking, syntax checking, linting, and jump to
definition/references.

Usage:

  Install Solargraph extension for your editor (see https://solargraph.org/guides)
  Run `bin/solargraph download-core` to install core Ruby language docs.
  Run `bin/solargraph bundle` to install Ruby gem docs.

See also:

* https://github.com/castwide/solargraph
* https://solargraph.org/guides/getting-started
* https://marketplace.visualstudio.com/items?itemName=castwide.solargraph

bin/solargraph

@@ -0,0 +1,29 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+#
+# This file was generated by Bundler.
+#
+# The application 'solargraph' is installed as part of a gem, and
+# this file is here to facilitate running it.
+#
+
+require "pathname"
+ENV["BUNDLE_GEMFILE"] ||= File.expand_path("../../Gemfile",
+  Pathname.new(__FILE__).realpath)
+
+bundle_binstub = File.expand_path("../bundle", __FILE__)
+
+if File.file?(bundle_binstub)
+  if File.read(bundle_binstub, 300) =~ /This file was generated by Bundler/
+    load(bundle_binstub)
+  else
+    abort("Your `bin/bundle` was not generated by Bundler, so this binstub cannot run.
+Replace `bin/bundle` by running `bundle binstubs bundler --force`, then run this command again.")
+  end
+end
+
+require "rubygems"
+require "bundler/setup"
+
+load Gem.bin_path("solargraph", "solargraph")