Rename HydratedTarget Resource and Chart to X

[olzemal]

Is your feature request related to a problem? Please describe.
Currently the hydrated-target gets rendered into a chart named ht-. This abbreviation was done do avoid hydrated-target being part of the chart url.

Describe the solution you'd like
Since the chart is used to bootstrap the cluster it would make sense to call it bootstrap.

Additional context
Stumbled across it in #102

Update:
As discussed during refinement, we want to also rename HydratedTarget!

AC:

• Decide on new name for resource
• Rename resource and chart
• Update tests and document as necessary

[trevex]

Does it makes sense to consider a different name all together for the custom resource as well? Bootstrap, Entrypoint, AppOfApps, App, ...

This might make the API actually easier to reason about...