add support for code block execution options

[maxim-uvarov]

Now it is possible to add execution options in the infostring of code block.

like ```nushell no-output

For now supported options are:

{
O: 'no-output' # don't try printing result
t: 'try' # try handling errors
n: 'new-instance' # execute outside
}

A user might use long or short form of an option. Options could be combined using comma, like in the example: ```nushell t, n