Use rxode2random R calls instead of ABI

[codecov[bot]]

Codecov Report

Base: 61.46% // Head: 61.33% // Decreases project coverage by -0.13% :warning:

Coverage data is based on head (181dd70) compared to base (656ab41). Patch coverage: 29.62% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #10 +/- ## ========================================== - Coverage 61.46% 61.33% -0.14% ========================================== Files 20 20 Lines 3932 3954 +22 ========================================== + Hits 2417 2425 +8 - Misses 1515 1529 +14 ``` | [Impacted Files](https://codecov.io/gh/nlmixr2/rxode2et/pull/10?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nlmixr2) | Coverage Δ | | |---|---|---| | [src/rxode2random.cpp](https://codecov.io/gh/nlmixr2/rxode2et/pull/10/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nlmixr2#diff-c3JjL3J4b2RlMnJhbmRvbS5jcHA=) | `29.62% <29.62%> (ø)` | | | [src/et.cpp](https://codecov.io/gh/nlmixr2/rxode2et/pull/10/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nlmixr2#diff-c3JjL2V0LmNwcA==) | `78.29% <0.00%> (+<0.01%)` | :arrow_up: | | [src/timsort.h](https://codecov.io/gh/nlmixr2/rxode2et/pull/10/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nlmixr2#diff-c3JjL3RpbXNvcnQuaA==) | `52.24% <0.00%> (+0.50%)` | :arrow_up: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nlmixr2). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nlmixr2)

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