feat(core): allow to create write API with custom writeOptions

[sranka]

Fixes #184

Proposed Changes

Adds optional writeOptions to getWriteApi

getWriteApi(
    org: string,
    bucket: string,
    precision: WritePrecision = WritePrecision.ns,
    writeOptions?: Partial<WriteOptions>
  ): WriteApi {

Checklist

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

[codecov-io]

Codecov Report

Merging #185 into master will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #185   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           26        26           
  Lines          767       768    +1     
  Branches       159       160    +1     
=========================================
+ Hits           767       768    +1     

Impacted Files	Coverage Δ
packages/core/src/options.ts	100.00% <ø> (ø)
packages/core/src/InfluxDB.ts	100.00% <100.00%> (ø)

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