Refactor and structure `access_control` implementation

[kushagra189]

Description

Access control needs to be a part of the security configuration and not a separate module. Hence, have refactored the implementation to pertain to the same.

Fixes #145

Type of change

Please delete options that are not relevant.

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Documentation update

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have updated the documentation (or documentation does not need to be updated)
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [x] I have not reduced the existing code coverage

[codecov[bot]]

Codecov Report

Base: 100.00% // Head: 100.00% // No change to project coverage :thumbsup:

Coverage data is based on head (808841f) compared to base (4549776). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev #149 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 20 20 Lines 966 967 +1 ========================================= + Hits 966 967 +1 ``` | [Impacted Files](https://codecov.io/gh/elixir-cloud-aai/foca/pull/149?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-cloud-aai) | Coverage Δ | | |---|---|---| | [.../access\_control/foca\_casbin\_adapter/casbin\_rule.py](https://codecov.io/gh/elixir-cloud-aai/foca/pull/149/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-cloud-aai#diff-Zm9jYS9zZWN1cml0eS9hY2Nlc3NfY29udHJvbC9mb2NhX2Nhc2Jpbl9hZGFwdGVyL2Nhc2Jpbl9ydWxlLnB5) | `100.00% <ø> (ø)` | | | [foca/foca.py](https://codecov.io/gh/elixir-cloud-aai/foca/pull/149/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-cloud-aai#diff-Zm9jYS9mb2NhLnB5) | `100.00% <100.00%> (ø)` | | | [foca/models/config.py](https://codecov.io/gh/elixir-cloud-aai/foca/pull/149/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-cloud-aai#diff-Zm9jYS9tb2RlbHMvY29uZmlnLnB5) | `100.00% <100.00%> (ø)` | | | [...a/security/access\_control/access\_control\_server.py](https://codecov.io/gh/elixir-cloud-aai/foca/pull/149/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-cloud-aai#diff-Zm9jYS9zZWN1cml0eS9hY2Nlc3NfY29udHJvbC9hY2Nlc3NfY29udHJvbF9zZXJ2ZXIucHk=) | `100.00% <100.00%> (ø)` | | | [foca/security/access\_control/constants.py](https://codecov.io/gh/elixir-cloud-aai/foca/pull/149/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-cloud-aai#diff-Zm9jYS9zZWN1cml0eS9hY2Nlc3NfY29udHJvbC9jb25zdGFudHMucHk=) | `100.00% <100.00%> (ø)` | | | [...rity/access\_control/foca\_casbin\_adapter/adapter.py](https://codecov.io/gh/elixir-cloud-aai/foca/pull/149/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-cloud-aai#diff-Zm9jYS9zZWN1cml0eS9hY2Nlc3NfY29udHJvbC9mb2NhX2Nhc2Jpbl9hZGFwdGVyL2FkYXB0ZXIucHk=) | `100.00% <100.00%> (ø)` | | | [...security/access\_control/register\_access\_control.py](https://codecov.io/gh/elixir-cloud-aai/foca/pull/149/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-cloud-aai#diff-Zm9jYS9zZWN1cml0eS9hY2Nlc3NfY29udHJvbC9yZWdpc3Rlcl9hY2Nlc3NfY29udHJvbC5weQ==) | `100.00% <100.00%> (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=elixir-cloud-aai). 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=elixir-cloud-aai)

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