Use namespace for analysis update

[eivindjahren]

Issue
Resolves #2575

Approach
Uses cpp namespace for analysis/update. Also removes static as we would like to test these functions and renames get_active_size to conform to standard cpp naming practices.

Pre review checklist

• Added appropriate labels

[codecov-commenter]

Codecov Report

Merging #2599 (59b91cb) into main (e0b23c6) will increase coverage by 0.03%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main    #2599      +/-   ##
==========================================
+ Coverage   60.53%   60.56%   +0.03%     
==========================================
  Files         336      336              
  Lines       37249    34747    -2502     
  Branches     4515     4229     -286     
==========================================
- Hits        22549    21046    -1503     
+ Misses      13314    12305    -1009     
- Partials     1386     1396      +10     

Impacted Files	Coverage Δ
libres/lib/analysis/update.cpp	0.00% <0.00%> (ø)
libres/lib/enkf/enkf_main.cpp	52.64% <0.00%> (-0.68%)	⬇️
libres/lib/include/ert/enkf/row_scaling.hpp	0.00% <0.00%> (-100.00%)	⬇️
libres/lib/include/ert/res_util/matrix.hpp	50.00% <0.00%> (-50.00%)	⬇️
libres/lib/enkf/value_export.cpp	58.49% <0.00%> (-15.24%)	⬇️
libres/lib/config/conf_util.cpp	55.55% <0.00%> (-14.60%)	⬇️
libres/lib/job_queue/forward_model.cpp	48.33% <0.00%> (-7.99%)	⬇️
libres/lib/analysis/ies/ies_enkf_data.cpp	83.00% <0.00%> (-7.06%)	⬇️
libres/lib/res_util/es_testdata.cpp	61.14% <0.00%> (-6.72%)	⬇️
libres/lib/job_queue/job_kw_definitions.cpp	60.00% <0.00%> (-6.67%)	⬇️
... and 135 more

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[dafeda]

Namespaces are nice, LGTM 👍