Declaring an action profile as a control local crashes the BMV2 backend

[sethfowler]

In #296 there was discussion of the fact that a table's implementation property could refer to a Declaration_Instance. The attached file is a modified version of an existing test case, action_profile-bmv2.p4, which declares an action profile as a control local. It crashes the BMV2 backend with this message:

../testdata/p4_16_samples/action_profile-bmv2.p4(41): error: implementation: expected constructor call for property
        implementation = ap;
        ^^^^^^^^^^^^^^
../testdata/p4_16_samples/action_profile-bmv2.p4(37): warning: Target does not support default_action for indirect (due to action profiles)
    table indirect {
          ^^^^^^^^
../testdata/p4_16_samples/action_profile-bmv2.p4(44): warning: Target does not support default_action for indirect_ws (due to action profiles)
    table indirect_ws {
          ^^^^^^^^^^^
libc++abi.dylib: terminating with uncaught exception of type Util::CompilerBug: COMPILER BUG: ../backends/bmv2/jsonconverter.cpp:1685
../testdata/p4_16_samples/action_profile-bmv2.p4(33): @name("ap") action_profile ap(128): not yet handled
    action_profile(32w128) ap;
                           ^^

Note that even ignoring the crash, the error implementation: expected constructor call for property suggests that we are currently not prepared to handle this case, at least in the BMV2 backend.

action_profile-bmv2.p4.txt