Added support of error suppression in inline expressions

[ziflex]

Added new syntax to suppress errors in inline expressions:

LET page = DOCUMENT(urlToFailedPage)?

RETURN page == NONE

LET page = DOCUMENT(url, { driver: "cdp" })

CLICK(page, "#button")

LET navigated = (WAITFOR EVENT "navigation" IN page)? == NONE

RETURN navigated

[codecov]

Codecov Report

Merging #671 (4f6a3d1) into master (72821e5) will increase coverage by 0.0%.
The diff coverage is 72.0%.

@@          Coverage Diff           @@
##           master    #671   +/-   ##
======================================
  Coverage    35.8%   35.9%           
======================================
  Files         348     349    +1     
  Lines       12612   12621    +9     
======================================
+ Hits         4520    4527    +7     
+ Misses       7661    7658    -3     
- Partials      431     436    +5