extension/src/goTest: preserve buildFlags as array when debugging tests

[vrv501]

The debugTestAtCursor CodeLens previously joined go.buildFlags into a
single space-separated string before passing them to the debug adapter.
This corrupted flag values that contain spaces, such as
-ldflags "-X pkg.version=v1.0": after joining, delve sees -X and
pkg.version=v1.0 as separate arguments and fails with "with multiple
packages, -o must refer to a directory or /dev/null".

Meanwhile, the run-test CodeLens passes each flag as a separate
argument to go test, so the same go.buildFlags worked for "run test"
but broke "debug test".

Fix:
Pass buildFlags as an array to startDebugging. The existing
maybeJoinFlags helper in goDebugConfiguration.ts already handles both
shapes: it joins for delve < 1.22.2 and preserves the array for newer
delve, so each element reaches delve as a separate token. Also omit
buildFlags from the debug config when empty to keep behavior parity
with the previous "" sentinel.

Fixes #3933

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Message from Gopher Robot:

Patch Set 1:

(1 comment)

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Message from Vaibhav:

Patch Set 1:

(2 comments)

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