For a hardcoded set of control characters, replace them with spaces when
encoding pasted text. This is to prevent unsafe control characters from being
pasted which could trick a user into executing commands unexpectedly.
This happens regardless of bracketed paste mode, because certain
characters processed by the kernel pty line discipline can break
bracketed paste (source from zsh:
https://zsh-workers.zsh.narkive.com/Kd3evJ7t/bracketed-paste-mode-in-xterm-and-urxvt).
This behavior is based on xterm's behavior, including the list of
characters. Note that as a comment in the code says, we should be
sourcing some of these from a tcgetattr call instead of hardcoding them,
but this is a good start.
This moves our paste logic to `src/input` in preparation for exposing
this as part of libghostty-vt. This yields an immediate benefit of
unit tests for paste encoding.
Additionally, we were able to remove one allocation on every unbracketed
paste path unless the input specifically contains a newline. Unlikely to
be noticable, but nice.
NOTE: This also includes one change in behavior: we no longer encode
`\r\n` and a single `\r`, but as a duplicate `\r\r`. This matches xterm
behavior and I don't think will result in any issues since duplicate
carriage returns should do nothing in well-behaved terminals.
