extension: add followExec and followExecRegex options in launch request

[Lslightly]

Add followExec and followExecRegex options in launch request in
launch.json. Before InitializedEvent is sent back from delve, followExec
and followExecRegex will be set in delve. If the program being
debugged spawns a new child process at the beginning and
breakpoints are set in source code line of child process, these
breakpoints will be hit and shown to the user.

Without these two options, although go-delve/delve#4078 provides
delve command to enable follow-exec in console, user have to
manually enable follow-exec in console each time launching the
debug session.

Fixes #3712

[gopherbot]

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[gopherbot]

Message from Gopher Robot:

Patch Set 1:

(1 comment)

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[gopherbot]

Message from Qingwei Li:

Patch Set 1:

(2 comments)

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Please don’t reply on this GitHub thread. Visit golang.org/cl/696795.
After addressing review feedback, remember to publish your drafts!