Review behavior of closing connections

[jreineckearm]

PR #522 has shown that the way of closing connections for gdbtarget across the entire stack VS Code/Theia -> GDB Adapter -> Stub/GDB server of your liking needs review and

• first proper documentation, would recommend to capture this in the repo Wiki.
• followed by discussion if and how to change things.

Main reason is multiple debugger protocols with variations in terminology and expected behavior come together for embedded targets, which haven't been a top priority when designing those (MSFT DAP, GDB-MI, GDB remote). And eventually may hit highly configurable GDB servers.

May become a delicate endeavor given the adapter is used in different use cases and products already.
Hence, I'd urge to move changes forward carefully. And it may make additional configurations necessary to preserve existing and fundamental use cases (least preferred but most likely outcome).

Also, it may have to include review of connection strategies because they can have impact on for example both DAP and GDB protocols.

CC: @jonahgraham , @cwalther , @datphan9798

[cwalther]

Part of the wiki documentation should probably be a glossary that defines common terms, to avoid unknowingly talking past each other. E.g. in the recent discussion, Jens has suggested “if you consider gdb server + target hardware as the "debugee"”, which would never have occurred to me – I thought with “debuggee” I had found an unambiguous word for “only the target hardware or process”.