Remove dependency on helidon.io from unit tests

[romain-grecourt]

Some cli unit tests rely on helidon.io and the published metadata to execute.

Sometime the test fails because the metadata update fails ; unit tests should be reliable and dissociated from the actual infrastructure.

E.g.

io.helidon.build.cli.impl.ArchetypeBrowserTest.testMpBrowser  Time elapsed: 0.821 s  <<< ERROR!
io.helidon.build.util.RequirementFailure: Helidon version 2.2.1 not found.
        at io.helidon.build.util.Requirements.failed(Requirements.java:63)
        at io.helidon.build.cli.impl.ArchetypeBrowser.<init>(ArchetypeBrowser.java:59)
        at io.helidon.build.cli.impl.ArchetypeBrowserTest.newBrowser(ArchetypeBrowserTest.java:35)
        at io.helidon.build.cli.impl.ArchetypeBrowserTest.testMpBrowser(ArchetypeBrowserTest.java:40)

Caused by:

stale check forced (not found) for /Users/rgrecour/workspace/helidon-build-tools/helidon-cli/impl/target/alice-11/.helidon/cache/2.2.1/.lastUpdate
Updating metadata for Helidon version 2.2.1
io.helidon.build.cli.impl.Plugins$PluginFailed: io.helidon.build.cli.plugin.Plugin$Failed: timeout accessing https://helidon.io/cli-data
        at io.helidon.build.cli.impl.Plugins.embedded(Plugins.java:156)
        at io.helidon.build.cli.impl.Plugins.execute(Plugins.java:134)
        at io.helidon.build.cli.impl.Plugins.execute(Plugins.java:113)
        at io.helidon.build.cli.impl.Metadata.update(Metadata.java:489)
        at io.helidon.build.cli.impl.Metadata.checkForUpdates(Metadata.java:399)
        at io.helidon.build.cli.impl.Metadata.checkForUpdates(Metadata.java:394)
        at io.helidon.build.cli.impl.Metadata.versionedFile(Metadata.java:389)
        at io.helidon.build.cli.impl.Metadata.catalogOf(Metadata.java:325)
        at io.helidon.build.cli.impl.Metadata.catalogOf(Metadata.java:314)
        at io.helidon.build.cli.impl.ArchetypeBrowser.<init>(ArchetypeBrowser.java:56)

We already have logic in place to run a local netty based http server as part of the unit tests, we need to expand its usage to all tests and figure out a proper way to test the actual helidon.io site.