If the long option name ends with an equals sign (`=`), the argument is
the text following on its right side.
This makes the command line parser accept this common style in addition
to the existing way to accept option arguments more similar to how other
command line tools do.
Example: `curl --user-agent=curl-2000 https://example.com/`
Change a few existing tests to use this syntax: 206, 1333, 1335, 1442
Closes#17789
