Fix remaining buffer serialization bugs

[lhecker]

It may be more accurate to say: "Fix known remaining buffer
serialization bugs", but I'll try to be positive about my code.

Initially, the buffer is initialized with the default attributes,
but once it begins to scroll, newly scrolled in rows are initialized
with the current attributes. This means we need to set the current
attributes to those of the upcoming row before the row comes up.

This is related to #17074.

Validation Steps Performed

• Persist and restore a buffer 10 times
• All previous "Restore" status messages look correct ✅
• The escape sequences in the buffer file look correct ✅

[zadjii-msft]

Does this actually close #17074 now?