feat: Set a user-specific crash dump directory

[gadenbuie]

Fixes #134

Sets --crash-dumps-dir for each session and uses tempfile() to create a consistent path name for a given session. (Previously, stdout and stderr would be written to log files with different "hashes".)

options(chromote.launch.echo_cmd = TRUE)
b <- ChromoteSession$new()
#> Running '/Applications/Google Chrome.app/Contents/MacOS/Google Chrome' \
#>   --headless '--remote-debugging-port=23311' \
#>   '--remote-allow-origins=http://127.0.0.1:23311' \
#>   '--crash-dumps-dir=/var/folders/yl/0xhq7c7n3z7_9hp1356kctbr0000gp/T//RtmpcsWZVF/chrome-bd71710535fb-crashpad' \
#>   '--force-color-profile=srgb' --disable-extensions --mute-audio

With this change, we now use the same tempdir prefix for all three session-specific files/directories:

• {tempdir}/chrome-bd71710535fb-crashpad/ for crash dumps
• {tempdir}/chrome-bd71710535fb-stdout.log
• {tempdir}/chrome-bd71710535fb-stderr.log