Update lcm-related bazel library names

[jwnimmer-tri]

Remove //util:lcm_util forwarding header, long since deprecated.

Rename //lcm:lcm to //lcm:real to clarify that it is only a concrete implementation of the interface, instead of everything in the package. Do not rename in-tree uses to match; they can use the package-level library without adding overly many spurious dependencies.

Rename //systems/lcm:lcm to //systems/lcm:lcm_pubsub to clarify that it is only the publisher and subscriber systems, instead of everything in the package. Rename all in-tree uses to match.

Add drake_cc_package_library for //lcm and //systems/lcm.

Builds on #8664. Relates #6464.

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This change is 

[jwnimmer-tri]

+@sammy-tri for all review, please.

[sammy-tri]

One minor question + one really minor BTW.

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Reviewed 20 of 20 files at r1.
Review status: all files reviewed at latest revision, all discussions resolved.

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lcm/BUILD.bazel, line 9 at r1 (raw file):

    "drake_cc_package_library",
)
load("//tools/skylark:drake_py.bzl", "drake_py_test")

BTW the spelling of the path to tools/skylark is now inconsistent in this file.

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tools/install/libdrake/build_components.bzl, line 110 at r1 (raw file):

    "//geometry:shape_specification",
    "//lcm:interface",
    "//lcm:lcm",

BTW Now that //lcm:lcm is the package library, are the entries below redundant? Or is the convention here to always list out all of the individual components even when the package library is included? (since it happens again below in //systems/lcm it seemed like it might be conventional)

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Comments from Reviewable

[sammy-tri]

Review status: all files reviewed at latest revision, all discussions resolved.

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tools/install/libdrake/build_components.bzl, line 110 at r1 (raw file):

Previously, sammy-tri (Sam Creasey) wrote…

BTW Now that //lcm:lcm is the package library, are the entries below redundant? Or is the convention here to always list out all of the individual components even when the package library is included? (since it happens again below in //systems/lcm it seemed like it might be conventional)

/me facepalm. It's autogenerated. Never mind.

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Comments from Reviewable

[jwnimmer-tri]

Review status: all files reviewed at latest revision, all discussions resolved, some commit checks failed.

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lcm/BUILD.bazel, line 9 at r1 (raw file):

Previously, sammy-tri (Sam Creasey) wrote…

BTW the spelling of the path to tools/skylark is now inconsistent in this file.

OK Hmm, I see that's a project-wide problem now. I'll open an issue => #8732.

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tools/install/libdrake/build_components.bzl, line 110 at r1 (raw file):

Previously, sammy-tri (Sam Creasey) wrote…

/me facepalm. It's autogenerated. Never mind.

OK Right! Also the work on #6464 actually makes it so all of the colon-library details here get eviscerated, very soon now.

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Comments from Reviewable

[sammy-tri]

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Reviewed 2 of 2 files at r2.
Review status: all files reviewed at latest revision, all discussions resolved.

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Comments from Reviewable