Add a simple read/parse plugin to better handle text data

[sophiajt]

This adds a simple read plugin which can handle a matching pattern. The pattern describes how to handle the text data and convert it to a table.

Let's say we had the following file:

VAR1=Chill
VAR2=StupidLongName
VAR3=AlsoChill

Usually, we would turn this into a table using:

open file.txt | lines | split-columns "=" Name Value

With this new command, we can instead give a simple pattern that the data must match. If it does, we take the row of text and convert it to structured data:

open file.txt | read "{Name}={Value}"

The {Name} and {Value} denote where the columns of those names will get their data.

If a line does not match the pattern, its data is not included in the table.

[gitpod-io]