Expressions: implement C++ literal arrays (whatever it means)
This should fix 4 tests:
https://github.com/kaitai-io/kaitai_struct_compiler/runs/4203900545?check_suite_focus=true#step:4:589
https://github.com/kaitai-io/kaitai_struct_compiler/runs/4203900545?check_suite_focus=true#step:4:692
https://github.com/kaitai-io/kaitai_struct_compiler/runs/4203900545?check_suite_focus=true#step:4:746
```
[info] - cpp_stl:[0, 1, 100500] *** FAILED ***
[info]   java.lang.RuntimeException: C++ literal arrays are not implemented yet
[info]   at io.kaitai.struct.translators.CppTranslator.doArrayLiteral(CppTranslator.scala:119)
[info]   at io.kaitai.struct.translators.CppTranslator.doArrayLiteral(CppTranslator.scala:15)
[info]   at io.kaitai.struct.translators.CommonArraysAndCast.doGuessArrayLiteral(CommonArraysAndCast.scala:41)
[info]   at io.kaitai.struct.translators.CommonArraysAndCast.doGuessArrayLiteral$(CommonArraysAndCast.scala:25)
[info]   at io.kaitai.struct.translators.BaseTranslator.doGuessArrayLiteral(BaseTranslator.scala:28)
[info]   at io.kaitai.struct.translators.BaseTranslator.translate(BaseTranslator.scala:137)
[info]   at io.kaitai.struct.translators.TranslatorSpec.$anonfun$runTest$3(TranslatorSpec.scala:646)
[info]   at org.scalatest.OutcomeOf.outcomeOf(OutcomeOf.scala:85)
[info]   at org.scalatest.OutcomeOf.outcomeOf$(OutcomeOf.scala:83)
[info]   at org.scalatest.OutcomeOf$.outcomeOf(OutcomeOf.scala:104)
[info]   ...

[info] - cpp_stl:[].as<u1[]> *** FAILED ***
[info]   java.lang.RuntimeException: C++ literal arrays are not implemented yet
[info]   at io.kaitai.struct.translators.CppTranslator.doArrayLiteral(CppTranslator.scala:119)
[info]   at io.kaitai.struct.translators.CppTranslator.doArrayLiteral(CppTranslator.scala:15)
[info]   at io.kaitai.struct.translators.CommonArraysAndCast.doCastOrArray(CommonArraysAndCast.scala:64)
[info]   at io.kaitai.struct.translators.CommonArraysAndCast.doCastOrArray$(CommonArraysAndCast.scala:53)
[info]   at io.kaitai.struct.translators.BaseTranslator.doCastOrArray(BaseTranslator.scala:28)
[info]   at io.kaitai.struct.translators.BaseTranslator.translate(BaseTranslator.scala:139)
[info]   at io.kaitai.struct.translators.TranslatorSpec.$anonfun$runTest$3(TranslatorSpec.scala:639)
[info]   at org.scalatest.OutcomeOf.outcomeOf(OutcomeOf.scala:85)
[info]   at org.scalatest.OutcomeOf.outcomeOf$(OutcomeOf.scala:83)
[info]   at org.scalatest.OutcomeOf$.outcomeOf(OutcomeOf.scala:104)
[info]   ...
[info] - cpp_stl:[].as<f8[]> *** FAILED ***
[info]   java.lang.RuntimeException: C++ literal arrays are not implemented yet
[info]   at io.kaitai.struct.translators.CppTranslator.doArrayLiteral(CppTranslator.scala:119)
[info]   at io.kaitai.struct.translators.CppTranslator.doArrayLiteral(CppTranslator.scala:15)
[info]   at io.kaitai.struct.translators.CommonArraysAndCast.doCastOrArray(CommonArraysAndCast.scala:64)
[info]   at io.kaitai.struct.translators.CommonArraysAndCast.doCastOrArray$(CommonArraysAndCast.scala:53)
[info]   at io.kaitai.struct.translators.BaseTranslator.doCastOrArray(BaseTranslator.scala:28)
[info]   at io.kaitai.struct.translators.BaseTranslator.translate(BaseTranslator.scala:139)
[info]   at io.kaitai.struct.translators.TranslatorSpec.$anonfun$runTest$3(TranslatorSpec.scala:639)
[info]   at org.scalatest.OutcomeOf.outcomeOf(OutcomeOf.scala:85)
[info]   at org.scalatest.OutcomeOf.outcomeOf$(OutcomeOf.scala:83)
[info]   at org.scalatest.OutcomeOf$.outcomeOf(OutcomeOf.scala:104)
[info]   ...

[info] - cpp_stl:[0, 1, 2].as<u1[]> *** FAILED ***
[info]   java.lang.RuntimeException: C++ literal arrays are not implemented yet
[info]   at io.kaitai.struct.translators.CppTranslator.doArrayLiteral(CppTranslator.scala:119)
[info]   at io.kaitai.struct.translators.CppTranslator.doArrayLiteral(CppTranslator.scala:15)
[info]   at io.kaitai.struct.translators.CommonArraysAndCast.doCastOrArray(CommonArraysAndCast.scala:64)
[info]   at io.kaitai.struct.translators.CommonArraysAndCast.doCastOrArray$(CommonArraysAndCast.scala:53)
[info]   at io.kaitai.struct.translators.BaseTranslator.doCastOrArray(BaseTranslator.scala:28)
[info]   at io.kaitai.struct.translators.BaseTranslator.translate(BaseTranslator.scala:139)
[info]   at io.kaitai.struct.translators.TranslatorSpec.$anonfun$runTest$3(TranslatorSpec.scala:646)
[info]   at org.scalatest.OutcomeOf.outcomeOf(OutcomeOf.scala:85)
[info]   at org.scalatest.OutcomeOf.outcomeOf$(OutcomeOf.scala:83)
[info]   at org.scalatest.OutcomeOf$.outcomeOf(OutcomeOf.scala:104)
[info]   ...
```
Relevant code:
https://github.com/kaitai-io/kaitai_struct_compiler/blob/0acfa60452a10b770a2c2e746f3de057f8ab76d9/shared/src/main/scala/io/kaitai/struct/translators/CppTranslator.scala#L119