RFR: 8356761: IGV: dump escape analysis information [v2]

[Anton Seoane Ampudia]

> This PR introduces new IGV dumps, property fields and filters related to escape analysis information.
> 
> The C2 escape analysis algorithm is carried out in six primary steps, of which many have interesting sub-steps (e.g. `split_unique_types`) or present an iterative nature where access to intermediate results can aid debugging and analysis. Additionally, escape analysis relies on an "intermediate structure" called the _connection graph_, which is also particularly valuable for deeper investigations.
> 
> With this changeset, escape analysis information is now dumped at key points throughout the algorithm, with a degree of granularity (from only the basic steps to in-detail iterative dumping). The dumps include several property fields, such as:
> 
> - Node escape “level”.
> - Scalar replaceability.
> - Node type within the connection graph (per [C2 Escape Analysis connection graph](https://wiki.openjdk.org/display/HotSpot/EscapeAnalysis)).
> 
> This is achieved by passing the `ConnectionGraph` in use to the `IdealGraphPrinter` during escape analysis, so that these properties can be dumped. After escape analysis, remaining interesting information that is left until macro elimination (and consequent elimination of non-escaping, replaceable allocations) is also dumped.
> 
> Additionally, two filters are provided: one for displaying the connection node type in the IGV node box, and another one for color-scaling nodes based on their escaping/scalar status.
> 
> **Testing:** passes tiers 1-3, manual testing in IGV

Anton Seoane Ampudia has updated the pull request incrementally with eight additional commits since the last revision:

 - Review comments: fix coloring
 - Review comments: general changes
 - Review comments: minor IGV changes
 - Review comment: update filter comment
 - Review comments: restore removed line
 - Review comments: small changes in idealGraphPrinter.cpp
 - Review comments: add node to dumps, split phase, general readjustments
 - Review comments: explicit null check

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/28060/files
  - new: https://git.openjdk.org/jdk/pull/28060/files/872b1b48..b7867f12

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28060&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28060&range=00-01

  Stats: 140 lines in 10 files changed: 74 ins; 37 del; 29 mod
  Patch: https://git.openjdk.org/jdk/pull/28060.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28060/head:pull/28060

PR: https://git.openjdk.org/jdk/pull/28060