feat: add Invocable scripts API

[bednar]

Proposed Changes

1. Added API for InvocableScripts.
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
• rake test completes successfully
• Commit messages are in semantic format
• Sign CLA (if not already signed)

[codecov-commenter]

Codecov Report

Merging #101 (f6dbac1) into master (141eb9f) will increase coverage by 0.02%.
The diff coverage is 60.56%.

@@            Coverage Diff             @@
##           master     #101      +/-   ##
==========================================
+ Coverage   50.23%   50.25%   +0.02%     
==========================================
  Files          62       63       +1     
  Lines        6336     6395      +59     
==========================================
+ Hits         3183     3214      +31     
- Misses       3153     3181      +28     

Impacted Files	Coverage Δ
lib/influxdb2/client/health_api.rb	100.00% <ø> (ø)
lib/influxdb2/client/ping_api.rb	100.00% <ø> (ø)
lib/influxdb2/client/invocable_scripts_api.rb	36.36% <36.36%> (ø)
lib/influxdb-client.rb	100.00% <100.00%> (ø)
lib/influxdb2/client/client.rb	100.00% <100.00%> (ø)
lib/influxdb2/client/default_api.rb	98.52% <100.00%> (-0.05%)	⬇️
lib/influxdb2/client/delete_api.rb	100.00% <100.00%> (ø)
lib/influxdb2/client/flux_csv_parser.rb	100.00% <100.00%> (ø)
lib/influxdb2/client/query_api.rb	94.73% <100.00%> (ø)

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[rhajek]

LGTM