[lldb-dap] Improve the runInTerminal ux. (#163830)
This updates lldb-dap to clear the screen when using `"console":
"integratedTerminal"` or `"console": "externalTerminal"`.
VSCode will reuse the same terminal for a given debug configuration.
After the process exits it will return to the shell but if the debug
session is launched again it will be invoked in the same terminal.
VSCode is sending the terminal the launch args as terminal input which
means the terminal would now have a string like `lldb-dap --comm-file
... --launch-target ...` and the scrollback buffer from any previous
output or shell commands used in the terminal.
To address this, I've updated LaunchRunInTerminalTarget to reset the
cursor, clear the screen and clear the scrollback buffer to soft 'reset'
the terminal prior to launching the process.
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Co-authored-by: Jonas Devlieghere <jonas@devlieghere.com>
