add nodex bindings

[uuhan]

Nodejs Napi Addon

const {sled} = require('./sled.node')

let db = new sled({
  path: "./index.db",
  use_compression: false,
})

let key = new TextEncoder().encode("hello").buffer
let value = new TextEncoder().encode("world").buffer

db.insert(key, value)
db.get(key)
db.remove(key)

let tree = db.open_tree('test-tree')
tree.insert(key, value)
tree.get(key)
tree.remove(key)

console.log(db.tree_names())