RFR: 8354196: C2: reorder and capitalize phase definition [v2]

[Manuel Hässig]

> This PR performs some cleanup and formatting around the phase definitions in C2:
>  - the phase descriptions are capitalized according to the [MLA Handbook title case rules](https://en.wikipedia.org/wiki/Title_case#Modern_Language_Association_(MLA)_Handbook),
>  - the phases are reordered to be more or less in the order of execution or occurrence in the code,
>  - the definitions in `phasetype.hpp` and `CompilePhase.java` are synced,
>  - `CompilePhase.java` is aligned for better readability.
> 
> This change was tested on:
>  - [x] [Github Actions](https://github.com/mhaessig/jdk/actions/runs/15605662671)
>  - [x] tier1 plus some Oracle internal testing

Manuel Hässig has updated the pull request incrementally with one additional commit since the last revision:

  Split-If is a proper name

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/25778/files
  - new: https://git.openjdk.org/jdk/pull/25778/files/54dbaabf..9f3676e4

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25778&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25778&range=00-01

  Stats: 4 lines in 2 files changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/25778.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25778/head:pull/25778

PR: https://git.openjdk.org/jdk/pull/25778