[Update Workflow] Phase 4: /etc/profile.d alias script

[darksidemilk]

Summary

Part of a 6-phase roadmap (see #1005 for Phase 1 and the full roadmap list).
Ships a generalized, distro-agnostic /etc/profile.d/fog.sh with shortcuts
for common admin tasks (updating, tailing logs), generalized from a personal
RHEL/site-specific alias file, so less-experienced Linux admins have an easy
on-ramp when asked for details/logs.

Design

• New function installProfileAliases(), called near the end of the main
  install flow (alongside installUtilities), rendering
  /etc/profile.d/fog.sh via a heredoc using the install's own resolved
  paths ($fogprogramdir, $fog_git_path from Phase 1, $webdirdest,
  $servicelogs) -- no hardcoded distro-specific or site-specific paths.
• Always regenerate the file fresh on install/update (it's fully derived, not
  meant to be hand-edited) -- safe and idempotent, same spirit as
  linkIfAbsent()'s re-run guarantee elsewhere in this codebase.
• Alias set, generalized from a personal fog.profile.sh down to what FOG
  itself manages:
  • fogupdate -> bash $fog_git_path/bin/updatefog.sh (Phase 1)
  • cdfog -> cd $fog_git_path
  • cdfogweb -> cd $webdirdest
  • fogupdatelog -> tail -n 200 -f $servicelogs/fogupdate.log (Phase 1's log)
  • fogerrorlog -> tail -n 200 -f $apacheerrlog (FOG's own
    per-distro-resolved web error log path, not a hardcoded php-fpm path)
  • Dropped, not generalized: the Arrowhead-specific PowerShell
    image-branch-promotion aliases, and the raw mysql -u root fog shortcut
    (assumes passwordless root -- not a safe default to ship broadly).
• No further wiring needed -- /etc/profile.d/*.sh is sourced automatically
  by login shells.

Files touched

• lib/common/functions.sh (new installProfileAliases() + call site)

Verification

• Fresh install, open a new login shell, confirm all aliases are present and
  each resolves to a correct path for that install.
• Test on at least one apt-based and one dnf-based distro to confirm the web
  error log path resolves correctly per distro.
• Re-run install/update and confirm the file is cleanly regenerated with no
  duplicated or stale entries from a prior install path.