Skip rft observations from csv if value -1

[HakonSohoel]

A value of -1 and error of 0 is used by fmu.tools.rms create_rft_ertobs to indicate missing data. If encountered in an rft observations csv file it should be skipped and create a user warning.

Issue
Resolves #12448

Approach
Added test to ensure rows with value -1 and error 0 are skipped with a warning
and added required functionality.

• PR title captures the intent of the changes, and is fitting for release notes.
• Added appropriate release note label
• Commit history is consistent and clean, in line with the contribution guidelines.
• Make sure unit tests pass locally after every commit (git rebase -i main --exec 'just rapid-tests')

When applicable

• When there are user facing changes: Updated documentation
• New behavior or changes to existing untested code: Ensured that unit tests are added (See Ground Rules).
• Large PR: Prepare changes in small commits for more convenient review
• Bug fix: Add regression test for the bug
• Bug fix: Add backport label to latest release (format: 'backport release-branch-name')

[eivindjahren]

I guess we will need this workaround for a while at least, but should we also change the creation of the csv file so that it does not include rows that are not correct? Thoughts @oyvindeide & @berland ?

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.64%. Comparing base (f0d9de4) to head (91b5825).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #12676      +/-   ##
==========================================
- Coverage   90.68%   90.64%   -0.04%     
==========================================
  Files         429      429              
  Lines       29808    29816       +8     
==========================================
- Hits        27030    27028       -2     
- Misses       2778     2788      +10     

Flag	Coverage Δ
cli-tests	37.55% <11.11%> (-0.01%)	⬇️
gui-tests	69.35% <11.11%> (-0.01%)	⬇️
performance-and-unit-tests	73.93% <100.00%> (+<0.01%)	⬆️
test	38.06% <11.11%> (-0.01%)	⬇️

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[codspeed-hq]

CodSpeed Performance Report

Merging this PR will not alter performance

_{Comparing HakonSohoel:ensure-compatibility-with-create_rft_ertobs-handling-of-missing-data (91b5825) with main (b34e318)}

Summary

✅ 22 untouched benchmarks

[berland]

"row" is an implementation detail. Should probably say something along: "The observation at that date will be ignored"