This is an attempt to fix this flakiness:
```
---- integration::repl::assign_underscore stdout ----
deno_exe path /home/runner/work/deno/deno/target/release/deno
command /home/runner/work/deno/deno/target/release/deno repl
command cwd /tmp/deno-cli-testK3YASC
------ Start Full Text ------
""
------- End Full Text -------
Next text: ""
thread 'integration::repl::assign_underscore' panicked at test_util/src/pty.rs:41:11:
Timed out.
stack backtrace:
```
Many of the CI tests have been failing on my M2 Pro mac (Ventura 13.4)
when running inside of a vscode terminal (a strange `ENOTTY` error).
This modifies the pty-handling code to use libc directly rather than the
older pty library that appears mostly unmaintained (outside of
@littledivy's fork).
As a bonus, this should allow us to run pty tests on the mac CI runner.
After this PR, the tests now complete with 100% success on my local
machine. Before this PR, I needed to pass `CI=true` to get my local test
suite to pass.
1. Fixes a cosmetic issue in the repl where it would display lsp warning
messages.
2. Lazily loads dependencies from the package.json on use.
3. Supports using bare specifiers from package.json in the REPL.
Closes #17929
Closes #18494
1. Rewrites the tests to be more back and forth rather than getting the
output all at once (which I believe was causing the hangs on linux and
maybe mac)
2. Runs the pty tests on the linux ci.
3. Fixes a bunch of tests that were just wrong.
4. Adds timeouts on the pty tests.
