build: print error if BuildKit/non-BuildKit-specific flags are used

[thaJeztah]

~depends on https://github.com/docker/cli/pull/2842~ merged fixes https://github.com/docker/cli/issues/2680 implements https://github.com/docker/cli/pull/1427#discussion_r224380101

With this patch, the --progress, --secret, --ssh, and --output flags trigger an error when trying to use without BuildKit enabled;

DOCKER_BUILDKIT=0 docker build --progress=plain .
--progress is only supported with BuildKit enabled. Enable BuildKit with DOCKER_BUILDKIT=1

DOCKER_BUILDKIT=0 docker build --output=foo . --output is only supported with BuildKit enabled. Enable BuildKit with DOCKER_BUILDKIT=1

Likewise, options that are not supported yet by BuildKit, now trigger an error:

DOCKER_BUILDKIT=1 docker build --memory=500M .
--memory is not supported with BuildKit enabled. Disable BuildKit with DOCKER_BUILDKIT=0

- What I did

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- Description for the changelog

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[thaJeztah]

@tiborvass @tonistiigi @silvin-lubecki PTAL

[thaJeztah]

Pushed a second commit to try integrating it with areFlagsSupported() however, that function is called by isSupported(), which is called by PersistentPreRunE, but I think we override that for build; checking now

[codecov-commenter]

Codecov Report

Merging #2736 into master will decrease coverage by 0.01%. The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #2736      +/-   ##
==========================================
- Coverage   57.15%   57.13%   -0.02%     
==========================================
  Files         297      297              
  Lines       18657    18663       +6     
==========================================
  Hits        10663    10663              
- Misses       7132     7136       +4     
- Partials      862      864       +2     

[thaJeztah]

opened https://github.com/docker/cli/pull/2737 to remove the pre-run hack

[thaJeztah]

Squashed the commits, and rebased on top of https://github.com/docker/cli/pull/2737 (that one needs to be merged first)

[silvin-lubecki]

@thaJeztah this PR needs a rebase 🦁

[thaJeztah]

@tiborvass PTAL

[tonistiigi]

The flags marked with no-buildkit annotation do not change the outcome of the build, with the exception of security-opt maybe. So I'm not in favor of erroring on them. Hiding should be enough to recommend not using them.

[thaJeztah]

Do you think we should print a warning? e.g. if someone expects to have set memory limits, but they are not applied?

[codecov-io]

Codecov Report

Merging #2736 (e2986f4) into master (51a0914) will decrease coverage by 0.01%. The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #2736      +/-   ##
==========================================
- Coverage   57.10%   57.08%   -0.02%     
==========================================
  Files         297      297              
  Lines       18635    18641       +6     
==========================================
  Hits        10642    10642              
- Misses       7134     7138       +4     
- Partials      859      861       +2