Add solana_clap_utils::hidden_unless_forced()

[ryoqun]

Problem

There's no nice way to forcibly expose all hidden args of CLI. It's desirable to see all sometimes for dev purpose.

Summary of Changes

Sneakily introduce such a mechanism

context: spin off from https://github.com/solana-labs/solana/pull/30746/files#r1140313895

[ryoqun]

@mvines thanks a lot. :)

[codecov]

Codecov Report

Merging #30843 (19e2ac8) into master (ac8c31b) will decrease coverage by 0.1%.
The diff coverage is 20.6%.

@@            Coverage Diff            @@
##           master   #30843     +/-   ##
=========================================
- Coverage    81.5%    81.5%   -0.1%     
=========================================
  Files         723      723             
  Lines      203473   203577    +104     
=========================================
+ Hits       165922   165935     +13     
- Misses      37551    37642     +91     

[CriesofCarrots]

Seems unlikely that most engs will know or remember to do this when adding a new hidden() tag, esp since most don't see all PR notifications like I do. But perhaps you are planning to audit every so often?

[ryoqun]

Seems unlikely that most engs will know or remember to do this when adding a new hidden() tag, esp since most don't see all PR notifications like I do. But perhaps you are planning to audit every so often?

yeah, i'll do manual audit for any in-flight .hidden(true) if any in open prs, like after 1 month? Then, I'm planning to eventually add a single git grep to sanity.sh.