Drop support for projections inside gems

To the best of my knowledge, zero gems have ever taken advantage of
this.

Replacement, in the unlikely event anyone needs it:

	let g:rails_gem_projections = {'foo': 'lib/projections.json'}

Author: tpope

autoload/rails.vim

@@ -4600,7 +4600,6 @@ let s:has_projections = {
       \  }
       \}
 
-let s:projections_for_gems = {}
 function! s:app_projections() dict abort
   let dict = s:combine_projections({}, s:default_projections)
   for [k, v] in items(s:has_projections)
@@ -4612,25 +4611,26 @@ function! s:app_projections() dict abort
   call s:combine_projections(dict, get(g:, 'rails_projections', ''))
   for gem in keys(get(g:, 'rails_gem_projections', {}))
     if self.has_gem(gem)
-      call s:combine_projections(dict, g:rails_gem_projections[gem])
+      try
+        if type(g:rails_gem_projections[gem]) ==# v:t_string
+          let file = g:rails_gem_projections[gem]
+          if file !~# '^\a\+:\|^/'
+            if !has_key(self.gems(), gem)
+              continue
+            endif
+            let file = self.gems()[gem] . '/' . file
+          endif
+          if file =~# '/$'
+            let file .= 'projections.json'
+          endif
+          call s:combine_projections(dict, rails#json_parse(s:readfile(file)))
+        else
+          call s:combine_projections(dict, g:rails_gem_projections[gem])
+        endif
+      catch
+      endtry
     endif
   endfor
-  let gem_path = escape(join(values(self.gems()),','), ' ')
-  if !empty(gem_path)
-    if !has_key(s:projections_for_gems, gem_path)
-      let gem_projections = {}
-      for path in ['lib/', 'lib/rails/']
-        for file in findfile(path.'projections.json', gem_path, -1)
-          try
-            call s:combine_projections(gem_projections, rails#json_parse(s:readfile(self.path(file))))
-          catch
-          endtry
-        endfor
-      endfor
-      let s:projections_for_gems[gem_path] = gem_projections
-    endif
-    call s:combine_projections(dict, s:projections_for_gems[gem_path])
-  endif
   if self.cache.needs('projections')
     call self.cache.set('projections', {})