optimizer: Julia-level escape analysis (rebase)

[ianatol]

This commit ports EscapeAnalysis.jl into Julia base.
You can find the documentation of this escape analysis at this GitHub page¹.

This escape analysis will hopefully be an enabling technology for various
memory-related optimizations at Julia's high level compilation pipeline.
Possible target optimization includes alias aware SROA (#43888),
array SROA (#43909), mutating_arrayfreeze optimization (#42465),
stack allocation of mutables, finalizer elision and so on².

The primary motivation for porting EA in this PR is to check its impact
on latency as well as to get feedbacks from a broader range of developers.
The plan is that we first introduce EA in this commit, and then merge the
depending PRs built on top of this commit like #43888, #43909 and #42465

This commit simply defines and runs EA inside Julia base compiler and
enables the existing test suite with it. In this commit, we just run EA
before inlining to generate IPO cache. The depending PRs, EA will be
invoked again after inlining to be used for various local optimizations.

Footnotes

1. The same documentation will be included into Julia's developer
   documentation by this commit. ↩

2. It would be also interesting if LLVM-level optimizations can consume
   IPO information derived by this escape analysis to broaden
   optimization possibilities. ↩

[ianatol]

Just rebases #43800 with the changes from #44008

[ianatol]

Might as well start nanosoldier here too, I guess:

@nanosoldier runtests(ALL, vs = ":master")
@nanosoldier runbenchmarks(!"scalar", vs=":master")

[ianatol]

Superseded by bad5206

[nanosoldier]

Your benchmark job has completed - possible performance regressions were detected. A full report can be found here.

[nanosoldier]

Your package evaluation job has completed - possible new issues were detected. A full report can be found here.