Implement oem type

[matzipan]

Closes #117

• [x] Add support for state vector parsing
• [x] Implement parser for state vector
• [x] Implement parser for covariance matrix
• [x] Add tests
• [x] Add rustdoc
• [x] Fix bug for missing segment
• [x] Add support for META_START/STOP
• [x] Implement construction for OemCovarianceMatrixType
• [x] Add support for COVARIANCE_START/STOP

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 98.23213% with 23 lines in your changes missing coverage. Please review.

Project coverage is 88.44%. Comparing base (4d9acef) to head (46235dd). Report is 8 commits behind head on main.

Files	Patch %	Lines
crates/lox-io/src/ndm/kvn/parser.rs	95.51%	16 Missing :warning:
crates/lox-io/src/ndm/oem.rs	99.35%	6 Missing :warning:
crates/lox-io/src/ndm/common.rs	75.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #130 +/- ## ========================================== + Coverage 84.92% 88.44% +3.51% ========================================== Files 84 84 Lines 37964 50981 +13017 ========================================== + Hits 32241 45090 +12849 - Misses 5723 5891 +168 ```

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[helgee]

Please prefix your branch names with your initials, e.g. az/implement_oem_type.