Improve autocompletion

[gmlarumbe]

It should be possible to improve autocompletion in a workspace by adding some modifications to function verilog-ext-workspace-capf in file verilog-ext-workspace.el:

• Detect if identifier at point is a queue/array/enum to complete with its builtin methods
• Autocomplete with directives after tick `
• Complete with system tasks after $: https://verificationacademy.com/forums/systemverilog/complete-list-system-functions-or-system-tasks-descriptions
• Class builtin methods (e.g. randomize())
• Remove class attributes/methods as candidates when using package scope completion
  • E.g: package my_pkg has a class named foo, with attribute attr1 and method new
  • Completion at point after my_pkg:: will show attr1 and new as candidates while it should only show foo