Docs: Add custom runtime image guide, maven guide, gradle guide, refactored native image guide.

[barchetta]

1. Add a new guide for custom runtime image creation (MP and SE)
2. Add new Maven and Gradle build guides. A little sparse for now, but it's a start.
3. Refactor native image guide to document both SE and MP
4. Shares content between MP and SE document by putting common content under common and using include and properties to generate edition specific document.
5. Fixed some typos in WebServer javadocs.

[romain-grecourt]

Typo in the title of the PR: customer -> custom.
We've been using the term 'flavor' for a while now, I think it's better to rename the *-edition attributes to *-flavor.

[batsatt]

I think it would also be worth showing passing script arguments, e.g. --test or --help just so it is clear how it is done, (and maybe that the port mappings isn't required).

[batsatt]

We have an open issue (#1391) about the right way to add configuration to the pom for these plugins, say if you want to disable CDS or whatever. Yes, properties work, but they're a bit of a pain. And just pointing to the plugin docs is confusing, since they talk about adding the profile, which is already present now.

It would be best if we could resolve that issue and then show how to do it here.

[barchetta]

We have an open issue (#1391) about the right way to add configuration to the pom for these plugins, say if you want to disable CDS or whatever. Yes, properties work, but they're a bit of a pain. And just pointing to the plugin docs is confusing, since they talk about adding the profile, which is already present now.

It would be best if we could resolve that issue and then show how to do it here.

I've add (an admittedly sparse) Maven Build Guide that shows examples of configuring the plugin and crossed referenced in the jlink guide.

[batsatt]

LGTM