builder/parser/dumper: Handle newlines appropriately.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
builder/parser: fix handling of empty strings as the only argument.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
builder: Fix a small bug that could improperly cache.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
builder: Fix entrypoint and cmd semantics in evaluator. Test c/o @cnf

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
evaluator: ensure entrypoint stays blank if set blank while CMD is set.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Do not populate path to prevent runconfig merge conflict; remove
autoConfig seeding of entrypoint.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
move entrypoint integration-cli test for blank entrypoint to separate function

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
builder: Fix an error check being done at the wrong spot in run
dispatcher

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Merge pull request #7806 from erikh/fix_cmd_handling_in_parser

Fix cmd and entrypoint handling in parser