buildx/build
Justin Chadwell a43d9a67c7 git: fix error wrapping to ensure internal errors are propogated
Also, tidy up the error printing, so that now we always print out the
"current commit information was not captured by the build" message,
instead of just for not locating the git binary.

Before:

	WARNING: buildx: git was not found in the system. Current commit information was not captured by the build

After:

	WARNING: current commit information was not captured by the build: git was not found in the system: <error message>

Signed-off-by: Justin Chadwell <me@jedevc.com>
..
build.go git: fix error wrapping to ensure internal errors are propogated
git.go git: fix error wrapping to ensure internal errors are propogated
git_test.go build: makes git dirty check opt-in
invoke.go build: rename ResultContext to ResultHandle
result.go remote controller: Fix entrypoint interaction bugs
url.go build: set remote bake def and remote dockerfile as internal solve
utils.go build: fix host-gateway handling