Enable JPMS and bump sslcontext-kickstart

[bjorndarri]

Modularisation:

1. Added module-info.java.
2. Upgraded sslcontext-kickstart to the modular 8.0.0 version.
3. Fixed imports to reflect package changes in sslcontext-kickstart.

Steps 2 and 3 perhaps belong in the Bump sslContextKickstart from 7.5.0 to 8.0.0 PR?

Other changes I had to make:

1. Version bumped to 5.5.1-SNAPSHOT.
2. mavenLocal() added to repositories, so I could refer to the 5.5.1-SNAPSHOT version of Javalin I built.
3. jetbrains.annotations added as a compileOnly dependency.

I ran into problems regarding Lombok, if I clean and build, the build fails with a bunch of module related errors both during compileJava and delombok, but the next time I build it succeeds, don't know what that's all about (never used Lombok before).

[codecov]

Codecov Report

Merging #85 (f218ab2) into dev (0105384) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##                dev      #85   +/-   ##
=========================================
  Coverage     90.96%   90.96%           
  Complexity       81       81           
=========================================
  Files             7        7           
  Lines           299      299           
  Branches         23       23           
=========================================
  Hits            272      272           
  Misses           22       22           
  Partials          5        5           

Flag	Coverage Δ
integrationTests	81.60% <ø> (ø)
unitTests	40.80% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...n/java/io/javalin/community/ssl/util/SSLUtils.java	85.50% <ø> (ø)

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