Enhance the search function for easymotion and support remote yank.

[feeiyu]

What this PR does / why we need it:

1. Enhance the search function for easy motion.

2. support remote yank

3. easy motion only search in visible area.

Which issue(s) this PR fixes fixes 8753

Special notes for your reviewer:

• Add background color configuration for matched characters. vim.easymotionIncSearchBackgroundColor

• The recommended custom mapping.

  "vim.normalModeKeyBindingsNonRecursive": [
    {
      "before": ["s"],
      "after": ["<leader>", "<leader>", "<leader>", "s"]
    },
    {
      "before": ["y", "r"],
      "after": ["<leader>", "<leader>", "<leader>", "y", "r"]
    }
  ]