Escaping issue with tag values

まだ誰も着手していません。

This issue occurs in our case because a user has entered specific meta data fields as just `\`.
According to the Influx docs, `\` does not need to be escaped, but may be.
In our case, however, the backslash is followed with a comma, because it is at the end of the tag value, followed by another tag value, leading to messed up interpretation of the whole record.

In my opinion, the safest way to handle this is to _always_ escape backslashes.

__Steps to reproduce:__
List the minimal actions needed to reproduce the behavior.

1. Create as `List<>` with at least one tag containing just a backslash `\`
2. Write this list to InfluxDB using
`client.getWriteApiBlocking().writeMeasurements(WriteParameters.DEFAULT_WRITE_PRECISION, myList);`

__Expected behavior:__
Data would be inserted correctly.

__Actual behavior:__
Influx returns:
`HTTP status code: 400; Message: unable to parse 'metrics,account.companyName=\,account.contactCity=\ [...]`

__Specifications:__
- Client Version: 6.7.0
- InfluxDB Version: 3.7
- JDK Version: 17
- Platform: Linux/Docker/openjdk:17-alpine

client.getWriteApiBlocking().writeMeasurements(...) から開始し、バックスラッシュだけを含む tag 値の後に別の tag が続くケースで失敗を再現します。その measurement がリクエスト送信前にどのようにシリアライズされるかを追跡し、結果の record が InfluxDB に受け入れられることを確認して、このケースのカバレッジを追加します。

索引モデルが issue の本文から書いたものです。