Set the icon name of the terminal
The icon name is what is displayed in iconified form of the terminal window and in window choosers / taskbars.
If title mode 0 (see set title mode) is set text is expect to be hex encoded (i.e. utf 8 with each code unit further encoded with two hex digits)
If title mode 2 (see set title mode) is set or the terminal is setup for unconditional utf-8 titles text is interpreted as utf-8. Else text is interpreted as latin1.
Only works when AllowTitleOps is set (default)
Maximum title length is 1024
non printable characters are replaced with '?'