* Implement a simple profiler for DAML scenarios

The profiler runs a single scenario and records timing information when
each function (and some other closures) are entered and left. The
resulting information can be visualized as a flamegraph using
[speedscope](https://www.speedscope.app/).

The profiler works by instrumenting the CEK machine at the heart of
DAML Engine. Unfortunetaly, this causes a very small overhead on
non-profiling runs too. However, in my benchmarks I could not measure
any significant impact on the overall runtime at all. More precisely,
the overhead is as follows:

Every closure now has an additional field called `label`. In
non-profiling runs this field is always set to `null`. This field needs
to be allocated, copied whenever we copy a closure and scanned during
garbage collection. Additionally, whenever we enter a closure, we check
this field and whenever it is _not_ `null`, i.e. never during
non-profiling runs, we record an "open event" and set up a hook for the
corresponding "close event". Thus, the additional cost during
non-profiling runs are a single pointer comparison and a jump beyond
the "then branch".

Since this is still very much in active development, there are no
documentation, other than an entry in a README, and no tests yet. They
will come before we promote this. However, the UX will look very
different then since we already have plans to significantly change it.

CHANGELOG_BEGIN
CHANGELOG_END

* Run scalafmt

* Make profiling argument to PureCompiledPackges optional

* Fix a bunch of tests

CHANGELOG_BEGIN
CHANGELOG_END

* scalafmt is so annoying

CHANGELOG_BEGIN
CHANGELOG_END

* Apply simple suggestions

CHANGELOG_BEGIN
CHANGELOG_END