feat(nodejs): introduce safer timestamp API

[puzpuzpuz]

Note. This is a breaking change, so the patch bumps the version to 2.0.0.

Adds time unit as an optional parameter to timestamp-accepting methods:

  const bday = Date.parse('1856-07-10');
  sender
    .table('inventors')
    .symbol('born', 'Austrian Empire')
    .timestampColumn('birthday', bday, 'ms') // notice 'ms' here
    .intColumn('id', 0)
    .stringColumn('name', 'Nicola Tesla')
    .at(Date.now(), 'ms'); // notice 'ms' here

The unit defaults to 'us' (native QuestDB resolution) in both timestampColumn() and at(). Supported values are:

• 'ns' - nanoseconds
• 'us' - microseconds
• 'ms' - milliseconds

Also, includes some code style changes (e.g. consistent ' instead of mixed ' and ") and a number of improvements, including example unification with the Java client.

Considered alternatives

Temporal types could be used instead of the optional parameter, but the thing is that the spec is still experimental, so it's too early to rely on it.