Smart/saved folders in dashboard page

[yousefakbar]

Add config options for smart/saved folders

Allow the user to add configuration for saved/smart folders with frequent/pre-saved queries and display them in the main Tags or notmuch-hello page

Example:

Add configuration options such as:

return {
    "yousefakbar/notmuch.nvim",
    opts = {
        notmuch_db_path = "/home/xxx/Documents/Mail",
        maildir_sync_cmd = "mbsync personal",
        keymaps = {
            sendmail = "<C-g><C-g>",
        },

        -- ADDED CONFIGURATION HERE --
        queries = {
          { name = "📤 Sent today", query = "tag:sent and date:today" },
          { name = "⚠️ IMPORTANT", query = "tag:flagged or tag:pr or tag:urgent" },
          { name = "⌛ Overdue (+3d)", query = "tag:inbox and date:..3d" },
        },
    },
}

Then in the dashboard notmuch-hello page, display/pin them at the top for easy use of frequent search queries:

Hints: <Enter>: Show threads | q: Close | r: Refresh | %: Refresh maildir | c: Count messages

Saved/Pinned:
-------------

📤 Sent today -- `tag:sent and date:today`
⚠️ IMPORTANT -- `tag:flagged or tag:pr or tag:urgent`
⌛ Overdue (+3d) -- `tag:inbox and date:..3d"`


Tags:
-----

inbox
unread
flagged
sent
.
.
.

With some extra cruft for displaying them nicely