RFR: 8339870: Remove yet more stale TODOs [v2]

[William Kemper]

> Final round of TODO removal.
> * Move asterisk for pointer next to type, not variable
> * Remembered set verifier uses a small 'scanner' abstraction to simplify reading of read or write card table
> 
> ## Testing
> 
> GHA, Internal pipelines

William Kemper has updated the pull request incrementally with one additional commit since the last revision:

  Move rset scan TODOs into ticket

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

Changes:
  - all: https://git.openjdk.org/shenandoah/pull/496/files
  - new: https://git.openjdk.org/shenandoah/pull/496/files/8719ba9d..135cc5ec

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=shenandoah&pr=496&range=01
 - incr: https://webrevs.openjdk.org/?repo=shenandoah&pr=496&range=00-01

  Stats: 15 lines in 1 file changed: 0 ins; 15 del; 0 mod
  Patch: https://git.openjdk.org/shenandoah/pull/496.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah.git pull/496/head:pull/496

PR: https://git.openjdk.org/shenandoah/pull/496