feat: add Invokable scripts API

[bednar]

Proposed Changes

1. Added API for InvokableScripts.
2. Changed supported InfluxDB version from InfluxDB 2.0 to InfluxDB 2.x

Checklist

• CHANGELOG.md updated
• Rebased/mergeable
• A test has been added if appropriate
• swift test completes successfully
• Commit messages are in semantic format
• Sign CLA (if not already signed)

[codecov-commenter]

Codecov Report

Merging #48 (5f50cff) into master (2d4ce6e) will decrease coverage by 14.42%.
The diff coverage is 22.72%.

@@             Coverage Diff             @@
##           master      #48       +/-   ##
===========================================
- Coverage   80.54%   66.11%   -14.43%     
===========================================
  Files          10       16        +6     
  Lines        1033     1278      +245     
===========================================
+ Hits          832      845       +13     
- Misses        201      433      +232     

Impacted Files	Coverage Δ
...ources/InfluxDBSwift/Generated/Models/Script.swift	0.00% <0.00%> (ø)
...DBSwift/Generated/Models/ScriptCreateRequest.swift	0.00% <0.00%> (ø)
...wift/Generated/Models/ScriptInvocationParams.swift	0.00% <0.00%> (ø)
...DBSwift/Generated/Models/ScriptUpdateRequest.swift	0.00% <0.00%> (ø)
...urces/InfluxDBSwift/Generated/Models/Scripts.swift	0.00% <0.00%> (ø)
Sources/InfluxDBSwift/InvokableScriptsAPI.swift	0.00% <0.00%> (ø)
Sources/InfluxDBSwift/QueryAPI.swift	64.42% <64.70%> (-5.98%)	⬇️
Sources/InfluxDBSwift/InfluxDBClient.swift	82.75% <82.60%> (-1.19%)	⬇️
Sources/InfluxDBSwift/FluxCSVParser.swift	94.85% <89.47%> (-1.34%)	⬇️
Sources/InfluxDBSwift/DeleteAPI.swift	79.72% <100.00%> (+0.27%)	⬆️
... and 1 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 2d4ce6e...5f50cff. Read the comment docs.

[bednar]

@rhajek this PR depends on #49