Given arguments that are not targeted for the wrapper script itself
needs to through the script and passed as given to the final call of the
Thunderbird binary. This needs the usage of the extra function call
'eval' to expand the given arguments first.

We also parse the arguments as a list instead on based the given
argument count. This saves a little bit time, the can loop directly
through the elements of list.
While looping through the arguments we search for escaped arguments and
"restore" this escaping as it is removed bx the shell. Doing this also
for arguments that containing some other special characters like equal
signs and commas. Some possible arguments for the thunderbird binary use
them. For example

  thunderbird -compose "to='recipient@tld.org','attachment=some.file'"

And doing some more escaping of used variables inside the script.

Closes: #855334