Create analyze_num_patients and correct ae* tables

[Melkiades]

Fixes #748

Note: this was done primarily for pagination issues (new tests target this precisely, see test_summarize_num_patients). Concurrently, also sorting is tested.

This PR must be followed by a couple of fixes and enhancements, listed here:

• fix # add_overall_col(label = "A+B") %>% # why this does not work in new test inside test_summarize_num_patients.R. not really a problem, wrong position of it
• modify original score_occurrences or add another score function that selects the columns (like my_score_occurences does at the moment). Modify and update score_occurrences so to have proper tests with different underlying rtables layouts to be sorted #785 (this was already there with the name score_occurences_cols, but the referred PR made other fixes along the way).
• test_score_occurences.R uses summarize in the "broken-pagination" way should be fixed along with the previous point.
• summarize_occurrences_by_grade has the same problem as summarize_num_patients and needs to be fixed in a separate PR to fix aet04. Fix summarize_occurrences_by_grade to work with pagination #783
• Update tests to check also correct indentation (cmt01 for example differs from others as the specific values are right indented by 1 space). Update table (and all) tests to check also correct indentation  #784
• Check all modified templates and have a PR there to update their behavior. https://github.com/insightsengineering/sme-tasks/issues/554

The last point involves (currently) the following templates:

• aet02
• aet02_smq
• aet_03
• aet_06_smq
• aet_09
• aet_09_smq
• mth01
• cmt01 (indentation is shifted to the right in second split -> different from other tables, to check)
• aet07
• aet06 (shifted indentation as in cmt01 but only for variant 1. Variant 3 and 5 have normal indentation)

All of the above-mentioned have in some way or another a possibly breaking pagination due to using summarize_row_groups before the split so that it would end wrongfully on all the pages.

@ayogasekaram fyi this PR contains also an enhancement for the function to_string_matrix with a handy way to copy-paste the result matrix (this is intended for a more general and practical fix of #784 and future uses.

[github-actions]

Unit Tests Summary

       1 files     127 suites   2m 35s ⏱️
   873 tests    873 ✔️ 0 💤 0 ❌
1 323 runs  1 323 ✔️ 0 💤 0 ❌

Results for commit fffa171.

♻️ This comment has been updated with latest results.

[ayogasekaram]

lgtm @Melkiades