Enhance shareable utility to override CICE ice_in options

[NickSzapiro-NOAA]

Commit Queue Requirements:

• This PR addresses a relevant WM issue (if not, create an issue).
• All subcomponent pull requests (if any) have been reviewed by their code managers.
• Run the full Intel+GNU RT suite (compared to current baselines), preferably on Ursa (Derecho or Hercules are acceptable alternatives). Exceptions: documentation-only PRs, CI-only PRs, etc.
  • Commit log file w/full results from RT suite run (if applicable).
  • Verify that test_changes.list indicates which tests, if any, are changed by this PR. Commit test_changes.list, even if it is empty.
• Transparency in the use of generative AI is required by NOAA policy. Was GenAI used in this work?
  • [Generative AI tool (insert name, if any)] was used to assist with developing this code. The code has been reviewed, edited, and validated by NWS staff.
• Fill out all sections of this template.

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Description:

Temporary AI description:

Summary:
Enhances recently added bash utility to handle both single-key overrides and multi-line block replacements for Fortran namelists (targeting ice_in).

Key Features:

Unified Workflow: Reads standard input (stdin) via a smart parser that can dynamically handle single lines (dt = 1800), full namelist blocks (&grid_nml ... /), or a mix of both.

Ordered Execution: Overrides are sequentially numbered and applied strictly top-to-bottom, guaranteeing deterministic outputs even when interleaving block and single-line overrides.

Fail-Fast Integrity: Validates all requested overrides. If a key or block is missing (e.g., due to a typo), throw error (exit 1) to halt execution, preventing unintended silent behavior.

HPC / CI Safe: Hardened against set -e traps, uses pure POSIX tools (sed, awk, grep) to avoid OS-specific regex issues, and securely cleans up temp directories. Built-in unit tests included.

Commit Message:

* UFSWM - 
  * AQM - 
  * CATChem - 
  * CDEPS - 
  * CECE - 
  * CICE - 
  * CMEPS - 
  * CMakeModules - 
  * UFSATM - 
    * ccpp-physics -
      * CCPP submodules (list) - 
    * atmos_cubed_sphere -
    * MPAS
  * GOCART -
  * LM4 - 
  * MOM6 - 
  * NOAHMP - 
  * WW3 - 
  * fire_behavior
  * stochastic_physics - 

Priority:

• Critical Bugfix: Reason
• High: Reason
• Normal

Git Tracking

UFSWM:

• Closes #

Sub component Pull Requests:

• UFSWM -
  • AQM -
  • CATChem -
  • CDEPS -
  • CECE -
  • CICE -
  • CMEPS -
  • CMakeModules -
  • UFSATM -
    • ccpp-physics -
      • CCPP submodules (list) -
    • atmos_cubed_sphere -
    • MPAS
  • GOCART -
  • LM4 -
  • MOM6 -
  • NOAHMP -
  • WW3 -
  • fire_behavior
  • stochastic_physics -
• None

UFSWM Blocking Dependencies:

• Blocked by #
• None

Documentation:

• Documentation update required.
  • Relevant updates are included with this PR.
  • A WM issue has been opened to track the need for a documentation update; a person responsible for submitting the update has been assigned to the issue (link issue).
• Documentation update NOT required.
  • Explanation:

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Changes

Regression Test Changes (Please commit test_changes.list):

• PR Adds New Tests/Baselines.
• PR Updates/Changes Baselines.
• No Baseline Changes.

Input data Changes:

• None.
• PR adds input data.
• PR changes existing input data.

Library Changes/Upgrades:

• Required
  • Library names w/versions:
  • Git Stack Issue (JCSDA/spack-stack#)
• No Updates

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Testing Log:

• RDHPCS
  • Orion
  • Hercules
  • GaeaC6
  • Derecho
  • Ursa
• WCOSS2
  • Dogwood/Cactus
  • Acorn
• CI
• opnReqTest (complete task if unnecessary)

Testing Remarks: