add print to Matcher

[mcakircali]

Description

Contributor Declaration

By opening this pull request, I affirm the following:

• All authors agree to the Contributor License Agreement.
• The code follows the project's coding standards.
• I have performed self-review and added comments where needed.
• I have added or updated tests to verify that my changes are effective and functional.
• I have run all existing tests and confirmed they pass.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.42%. Comparing base (2384341) to head (cb01ae2).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #208      +/-   ##
===========================================
+ Coverage    73.36%   73.42%   +0.05%     
===========================================
  Files          126      126              
  Lines         8137     8154      +17     
  Branches       778      779       +1     
===========================================
+ Hits          5970     5987      +17     
  Misses        2167     2167              

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[Copilot]

Pull request overview

This PR adds stream-printing support to metkit::mars::Matcher to make match conditions easier to inspect/debug via std::ostream output.

Changes:

• Adds Matcher::print(std::ostream&) const and an inline operator<< overload in Matcher.h.
• Implements Matcher::print() in Matcher.cc to format the internal regexMap_ as {key=regex,...}.

mars2grib documentation synchronization (Guideline 1000000):

• Impacted files under src/metkit/mars2grib/**: none
• Documentation status: ✅ in sync (no mars2grib-facing changes)

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/metkit/mars/Matcher.h	Adds print() declaration and operator<< overload for Matcher.
src/metkit/mars/Matcher.cc	Implements Matcher::print() to stream the matcher’s key/regex map.

[danovaro]

lgtm, thanks @mcakircali !