Add `ar1_noise` synth. data routine

[tensionhead]

Changes Summary

• also renamed AR2_network to ar2_network

Reviewer Checklist

• [ ] Are testing routines present?
• [ ] Do objects in the global package namespace perform proper parsing of their input?
• [ ] Are all docstrings complete and accurate?
• [ ] Is the CHANGELOG.md up to date?

[codecov[bot]]

Codecov Report

Patch coverage: 54.54% and project coverage change: +0.08 :tada:

Comparison is base (ad755d6) 68.95% compared to head (7087029) 69.03%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev #503 +/- ## ========================================== + Coverage 68.95% 69.03% +0.08% ========================================== Files 87 87 Lines 10162 10164 +2 Branches 2073 2072 -1 ========================================== + Hits 7007 7017 +10 Misses 2617 2617 + Partials 538 530 -8 ``` | [Impacted Files](https://app.codecov.io/gh/esi-neuroscience/syncopy/pull/503?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esi-neuroscience) | Coverage Δ | | |---|---|---| | [syncopy/synthdata/utils.py](https://app.codecov.io/gh/esi-neuroscience/syncopy/pull/503?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esi-neuroscience#diff-c3luY29weS9zeW50aGRhdGEvdXRpbHMucHk=) | `100.00% <ø> (ø)` | | | [syncopy/tests/backend/test\_fooofspy.py](https://app.codecov.io/gh/esi-neuroscience/syncopy/pull/503?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esi-neuroscience#diff-c3luY29weS90ZXN0cy9iYWNrZW5kL3Rlc3RfZm9vb2ZzcHkucHk=) | `85.00% <0.00%> (ø)` | | | [syncopy/tests/local\_spy.py](https://app.codecov.io/gh/esi-neuroscience/syncopy/pull/503?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esi-neuroscience#diff-c3luY29weS90ZXN0cy9sb2NhbF9zcHkucHk=) | `0.00% <ø> (ø)` | | | [syncopy/synthdata/analog.py](https://app.codecov.io/gh/esi-neuroscience/syncopy/pull/503?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esi-neuroscience#diff-c3luY29weS9zeW50aGRhdGEvYW5hbG9nLnB5) | `72.05% <50.00%> (-3.75%)` | :arrow_down: | | [syncopy/tests/backend/test\_conn.py](https://app.codecov.io/gh/esi-neuroscience/syncopy/pull/503?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esi-neuroscience#diff-c3luY29weS90ZXN0cy9iYWNrZW5kL3Rlc3RfY29ubi5weQ==) | `100.00% <100.00%> (ø)` | | ... and [4 files with indirect coverage changes](https://app.codecov.io/gh/esi-neuroscience/syncopy/pull/503/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=esi-neuroscience)

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