BREAKING CHANGE: Use create request body instead of custom parameters

[Fank]

Description

Please describe what does this Pull Request fix or add?.

atm the use of custom fields is impossible, because the value could only be a string, so a field with type option-with-child which requires a { "value": "foo" } as value wont work.
By allowing such change, the struct needed to changed so it would be a breaking change anyway.
While doing that i also removed all parameters which are a "part" of the struct and put them together.

Information that is useful here:

• The What: What is your change doing?

Allowing to transfer more complex custom field values

• The Why: Why is your change useful/needed? What is your use case? (this helps us to understand the real world better)

Currently only the value string can be used, but more complex structure is needed to for custom fields.
And the request struct type which was given is not the same which is mentioned in the jira docs, so i changed the field structure to match it again.

• Type of change: Things like Bugfix, New feature, Code quality improvements, Dependency upgrade, Documentation, ...

New feature
Code quality improvements

• Breaking change: Yes or no? Backward compatible?

Yes, no backward compatibility

• Related to an issue: Does this fix or close an issue? Or is related in any kind?

Not directly, maybe:

• How whe can get custom fields values? #417
• Custom fields not being written, and creating issues returns an incorrect *jira.Issue with nil fields #380

• Jira Version + Type: Which Jira version and type (on-premise / cloud) you have used?

Cloud

Example:

Let us know how users can use or test this functionality.

// Example code

Checklist

• Unit or Integration tests added
  • Good Path
  • Error Path
• Commits follow conventions described here:
  • Conventional Commits 1.0.0
  • The seven rules of a great Git commit message
• Commits are squashed such that
  • There is 1 commit per isolated change
• I've not made extraneous commits/changes that are unrelated to my change.

[andygrunwald]

Hey,

I am very sorry that this pull request has been open for a long time with no final feedback or merge/decline. We work on this project in our spare time, and sometimes, other priorities take over. This is the typical open source dilemma.

However, there is news: We are kicking off v2 of this library 🚀

To provide visibility, we created the Road to v2 Milestone and calling for your feedback in #489

The development will take some time; however, I hope you can benefit from the changes.
If you seek priority development for your pull request + you like to sponsor it, please contact me.

What does this mean for my pull request?

We will work on this pull request indirectly.
We might merge it during the development or pull parts of it into the new version.
This means that during the development phase, we aim to tackle it.
Maybe in a different way like it is currently handled.
Please understand that this will take a while because we are running this in our spare time.

Final words

Thanks for using and contributing to this library.
If there is anything else you would like to tell us, let us know!