feat: Add helpful tooltips for the key features

[BrunoQuaresma]

• Add PageHeader component
• Add HelpTooltip component

Closes #1640

[tjcran]

@BrunoQuaresma the resource tooltip looks good to me! The template tooltip, I think it's better if we remove the second sentence and just end with the word "terraform". What do you think?

[bpmct]

Maybe just one link to the templates doc for now labeled "managing templates"?

https://github.com/coder/coder/blob/main/docs/templates.md#templates

[BrunoQuaresma]

Ahh, this one is just a sample. I'm already using this link for the templates:

 <HelpTooltipLink href="https://github.com/coder/coder/blob/main/docs/templates.md#manage-templates">
  Manage templates
</HelpTooltipLink>

[Kira-Pilot]

I think we could use some Language objects for the tooltip copy. I understand the tooltip copy is still be reviewed but once that's refined, this looks great from a FE perspective!