Ignore certain lines when styling

[lorenzwalthert]

Closes #365 as well as it's duplicates #533 and #542, following the #365 (comment). Here is a short example of how to use it, it works both for segments as well as inline:

call(1 ) # styler: off
# styler: off
# also if there are more comments
test_xkj("hier", na.rm = 3, py = 43
         )

x="new" # styler: off
y=1 # none

more_calls(with(arguments))
# styler: on
1 + 1
a(!b)

Taken from the outline in #365, this PR implements the functionality as follows:

Here is how to make sure this code does not get styled:

• Before parse data is nested, we find the stylerignore tags and add a column
  stylerignore to the parse data which is false for all token except the
  tokens that fall between two stylerignore tags.

• After code is turned into nested parse data and spaces and newlines are
  computed (must be between terminals, not between any token as currently done with
  default_style_guilde_attributes() edit: Because we need the position of tokens relative to other terminals, not tokens in general when serializing, we must do default_style_guilde_attributes() twice in total now). We store the lag_spaces and
  lag_newline attributes for all terminal tokens that are marked as
  stylerignore in the environment env_current.

• We proceed as usual with appyling transformers and flattening out the parse
  table.

• Right before we serialize the parse table, we replace lag_newlines, lag_spaces
  and tokens, text with the initial values for all tokens that were marked as
  stylerignore. Then we serialize.

[lorenzwalthert]

Say in documentation that this function modifies env_current.