Add find_all to eregmatch() nasl function

[jjnicola]

What:
Add find_all to eregmatch() nasl function

Jira: SC-395

Why:
The current implementation only returns the first match in the string.
Now it will return all matches if the option find_all: TRUE is passed to the function.
For backward compatibility, if FALSE is passed or no option, it will return the first match as before.

How:
Run the following nasl script with openvas-nasl without the option, with the option set FALSE/TRUE

foo = "11 abc
22 def
221 def
222 def
223 def
224 def
225 def
3333 ghi";
bar = eregmatch(string:foo, pattern:"[0-9]+", find_all: TRUE);
#display(foo);
display(bar);

Checklist:

• Tests
• CHANGELOG Entry