remove and clean up GeneAssociations alias

[exaexa]

• it was too similar to GeneAssociationsDNF
• Vector{Isozyme} actually explains the contents very well, and no complexity is hidden

[codecov[bot]]

Codecov Report

Base: 88.44% // Head: 88.44% // No change to project coverage :thumbsup:

Coverage data is based on head (9f57b0b) compared to base (8484eb3). Patch coverage: 0.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## next #753 +/- ## ======================================= Coverage 88.44% 88.44% ======================================= Files 88 88 Lines 2095 2095 ======================================= Hits 1853 1853 Misses 242 242 ``` | [Impacted Files](https://codecov.io/gh/LCSB-BioCore/COBREXA.jl/pull/753?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LCSB-BioCore) | Coverage Δ | | |---|---|---| | [src/types/GeneAssociations.jl](https://codecov.io/gh/LCSB-BioCore/COBREXA.jl/pull/753?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LCSB-BioCore#diff-c3JjL3R5cGVzL0dlbmVBc3NvY2lhdGlvbnMuamw=) | `100.00% <ø> (ø)` | | | [src/types/Reaction.jl](https://codecov.io/gh/LCSB-BioCore/COBREXA.jl/pull/753?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LCSB-BioCore#diff-c3JjL3R5cGVzL1JlYWN0aW9uLmps) | `100.00% <ø> (ø)` | | | [src/types/misc/gene\_associations.jl](https://codecov.io/gh/LCSB-BioCore/COBREXA.jl/pull/753?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LCSB-BioCore#diff-c3JjL3R5cGVzL21pc2MvZ2VuZV9hc3NvY2lhdGlvbnMuamw=) | `95.34% <0.00%> (ø)` | | | [src/types/models/MatrixModel.jl](https://codecov.io/gh/LCSB-BioCore/COBREXA.jl/pull/753?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=LCSB-BioCore#diff-c3JjL3R5cGVzL21vZGVscy9NYXRyaXhNb2RlbC5qbA==) | `96.66% <ø> (ø)` | | 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=LCSB-BioCore). 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=LCSB-BioCore)

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