Add extension jackson-jr-extension-javatime to support (some) Java 8 date/time types

[Shounaks]

Sorry about previous tries, I believe this might suffice.
Regarding Issue #100

[cowtowncoder]

Quick note: I fixed issue with CI failures (a regression in jackson-core), so now all tests pass as expected.

[cowtowncoder]

First of all: thank you for contributing this, @Shounaks !
This sounds good overall; I'll need to go through it but I think the idea works well.
About the only immediate thing I noticed is that we need Moditect definition under

 ..../src/moditect/module-info.java

(see examples of f.ex jr-annotation-support/)

Aside from that, one thing we need is CLA, from:

https://github.com/FasterXML/jackson/blob/master/contributor-agreement.pdf

and it only needs to be sent once before the first contribution. Usually it's easiest to print, fill & sign, scan/photo, email to cla at fasterxml dot com.

Thank you again; I am looking forward to getting this merged for inclusion in 2.17.0 release!

[cowtowncoder]

Ok, one more thing: I think main README.md should be modified to add brief explanation of the new extension. And there should be small jr-extension-datetime/README.md as well.

I will also remove JDK 20 references; package is still JDK 8 compatible for Jackson 2.x

[cowtowncoder]

Looks good; if we can get CLA sorted out I think I should be able to merge this!

[Shounaks]

There is one more thing I would like to add, if you permit. that would be custom formatter support for this functionality

so using this, the developer would have a control on the format data is is coming on. I am sharing its patch file as well, feel free to tell me what you think about it.

Adding_Custom_Formatter_Support_for_LocalDateTime.patch

[cowtowncoder]

Sure, the idea of configurability sounds reasonable. One thing I would suggest, however, is to not call formatter DEFAULT_FORMATTER and assume it is used for everything, since if and when adding new types they will need different formatters.

So I would probably add separate setter method for configuring DateTimeFormatter for LocalDateTime.

.... actually, I only now realize that the provider probably should be renamed too, not to be just for LocalDateTime. I think it should be something more generic.

[cowtowncoder]

First of all: thank you @Shounaks for contributing this! It will be in Jackson 2.17.0 rc1 to be released soon.

One thing: I Merged before remembering to ask or one thing -- basic set of unit tests would be nice, if possible (via different PR)?