Enhancement request: Select a specific tab for `bt text`

[doronbehar]

As somewhat discussed in https://github.com/balta2ar/brotab/issues/15#issuecomment-571953200, It would be nice to be able to select a specific tab to get the text of when using bt text. I was thinking of an updated cli usage such as:

$ bt text --help
usage: bt text [-h] [--tsv TSV] [--cleanup] [--tab TAB]

optional arguments:
  -h, --help  show this help message and exit
  --tsv TSV   tsv file to save results to
  --cleanup   force removal of extra whitespace
  --tab       choose a specific tab by it's ID.
              use 'bt list' to view the options, or use --tab=active

[doronbehar]

Thanks @balta2ar !