Implement host prefix cmds

[tschak909]

At @FozzTexx ask, implement get and set host prefixes for all current lib targets.

Apple still needs addit'l commands in firmware added for get host prefix.

[FozzTexx]

Apple still needs addit'l commands in firmware added for get host prefix.

To add the host prefix stuff to Apple II on my unified fuji device branch, all I had to do was add these 3 lines to iwmFuji:

+        { FUJICMD_GET_HOST_PREFIX, [this]()            { this->fujicmd_get_host_prefix(data_buf
fer[0]); }},                  // 0xE0
+        { FUJICMD_SET_HOST_PREFIX, [this]()            { this->fujicmd_set_host_prefix(data_buf
fer[0], (const char *) &data_buffer[1]); }},          // 0xE1
+        { FUJICMD_GET_HOST_PREFIX, [this]()            { }},                  // 0xE0

[markjfisher]

this isn't required anymore, the values are immediately set

[markjfisher]

remove the comment

[markjfisher]

I've avoided using malloc in library. it pulls a huge chunk of cc65 into the application and is much better just using a static array.

[markjfisher]

ditto (just trying to tag them all)