feat(dsl): standard library — movement actions (p7-s5)

[JArmandoAnaya]

Slice 43f of #43. §8.8.2–§8.8.4 as bundled DSL source: 15 actions for
movable_object, 13 for vehicle, walk for person, and the four
enums they use (dynamic_profile, lane_change_side, gap_direction,
headway_direction).

Two bases the standard names but never declares

§8.8.1 gives osc_action exactly two children, action_for_environment and
action_for_movable_object (both landed in 43d). §8.8.3 and §8.8.4 then name
action_for_vehicle and action_for_person in their "Parents" rows, and no
table declares either. §8.8.1's prose supplies them: "Actions for actors that
are children of movable_object, like vehicle or person, inherit from
action_for_movable_object."

Fourteen actions would otherwise have no parent to name, so both are declared
here and their placement is pinned by test.

Judgement calls

Each is recorded in the worksheet with the row that forced it.

• Mutually exclusive parameters are still plain fields. §8.8.2.4 says "use
  only one of the three possible arguments"; replay_path marks both
  absolute and relative mandatory though only one can be supplied. The
  language has no choice-group construct, and §7.3.11 already lets a scenario
  leave a field unconstrained. Same rule that made every table row a field in
  43b.
• change_position.target_xyz is marked deprecated in the same row that
  declares it, in favour of target_position. Both are declared: there is no
  deprecation marker in the language, and dropping a field the standard prints
  would reject a conforming scenario. Reporting the deprecation belongs to a
  later pass.
• change_lane.reference documents Default=it.actor. A default naming the
  invoking actor is not a constant expression, so none is declared — the field
  is simply left unconstrained, which is what §7.3.11 already means.
• The change_*/keep_* gap pairs take different direction enums. A
  change_time_gap takes the six-valued gap_direction; keep_time_gap takes
  the two-valued road_distance_direction (§8.7.22). Carried as printed and
  pinned by TheChangeAndKeepActionsTakeDifferentDirectionEnums, because it
  reads like an oversight and someone will otherwise "fix" it.

Actions and modifiers may share a simple name

change_speed, keep_speed and change_lane are actions here and modifiers in
§8.9. They do not collide: an action's name is a qualified behavior name
(§7.2.2.2.5), so this chapter declares movable_object.change_speed while §8.9
will declare a plain change_speed. AnActionAndAModifierMayShareASimpleName
pins both directions — the qualified name exists, the unqualified one does not
yet — so the next slice cannot blur the distinction.

ADirectionLiteralNeedsItsEnumName covers the other consequence of this
chapter: left is now a member of four enums and ahead of two, so §7.3.3's
qualification is the normal case rather than the exception.

The reading technique, written down

§8.8 is 2190 lines. Its normative tables are 725 of them; the rest is worked
examples, which are illustrative and not what a translation needs. Dropping the
Examples subsections before reading is the difference between "too big for one
sitting" and "one sitting", and docs/dev/stdlib-worksheets/README.md now says
so with the one-liner that does it.

The examples still earn a second pass — §8.15.10's showed which actor the
traffic-light actions hang off, and §8.12.2's showed create_route being called
with fewer arguments than it declares — but they are not the first pass.

Tests

frontends/dsl/tests/dsl_stdlib_test.cpp, +8 cases: the intermediate bases and
their place in the hierarchy; every movable_object, vehicle and person
action with its parent and parameter count; the change/keep direction
asymmetry; the four enums; the deprecated parameter; the action-vs-modifier
name distinction; and the new enum ambiguity in both directions.

1278 gtest (+8), 184 pytest. TheBundledLibraryChecksClean still asserts
zero diagnostics of any severity.

Docs: osc-dsl-coverage.md, the new worksheet, and the worksheet README.

Refs #43