Upgrade to Bazel 6.0

[jwnimmer-tri]

WIP for CI testing

See bazelbuild/bazel issue for upstream release information.

Requires fixes:

• [workspace] Add dependency on bazelbuild/platforms #18250
• [lint] Tidy up genquery input #18253

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This change is 

[jwnimmer-tri]

@drake-jenkins-bot linux-focal-unprovisioned-gcc-bazel-experimental-release please

[jwnimmer-tri]

Closing until 6.0.0rc2 comes out.

[jwnimmer-tri]

6.0.0rc2:

@drake-jenkins-bot linux-focal-unprovisioned-gcc-bazel-experimental-release please
@drake-jenkins-bot mac-x86-monterey-clang-bazel-experimental-release please

[jwnimmer-tri]

macOS analysis error:

ERROR: external/dreal/dreal/api/BUILD.bazel:17:17: Illegal ambiguous match on configurable attribute "copts" in @dreal//dreal/api:api:
@dreal//tools:clang_build
@dreal//tools:apple
Multiple matches are not allowed unless one is unambiguously more specialized.

Probably due to this bazel change:

The @bazel_tools//tools/cpp:compiler flag now has the value clang for the auto-configured Xcode toolchain rather than the generic value compiler. A branch for clang may have to be added to select statements that do not have a default case that handles this toolchain appropriately.

[jwnimmer-tri]

New error on Ubuntu: bazelbuild/bazel#16796.