install: search when formula isn't found.

If you do `brew install blah` it currently doesn't search for it. This
seems to be unintentional looking at this code as the exception thrown
by ARGV.formulae.each is not caught and handled. Instead, let's handle
this case and provide a little more usability around our taps.

Closes Homebrew/homebrew#31761.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Library/Homebrew/cmd/install.rb

@@ -24,6 +24,7 @@ module Homebrew
       end
     end unless ARGV.force?
 
+    begin
       ARGV.formulae.each do |f|
         # Building head-only without --HEAD is an error
         if not ARGV.build_head? and f.stable.nil?
@@ -41,7 +42,6 @@ module Homebrew
 
       perform_preinstall_checks
 
-    begin
       ARGV.formulae.each { |f| install_formula(f) }
     rescue FormulaUnavailableError => e
       ofail e.message