Enhancement: Prop to constrain height of combobox menus

[paulcpederson]

Description

Currently the max-height of an open dropdown is 90vh and the combobox list is 100vh. This is generally not desirable as the chances that the item is at the very top of the screen and you'd like it to take up the full screen is slim to none.

We should provide a max-items prop so that devs can style these UI's in ways that make sense for their application.

Acceptance Criteria

<calcite-combobox max-items="5"></calcite-combobox> will show five items and the rest will be available via scroll.

Relevant Info

#396 : issue about large scrolling dropboxes
#431 : issue about max-height in dropboxes
#195 : popover going off-screen

Which Component

calcite-combobox

Example Use Case

Combobox at the bottom of a form:

Height is full screen height, so entire dialog will scroll to cover it:

Then there is even more because it's not constrained to the container, but rather the screen:

[paulcpederson]

Dropbox has this already! Just noticed, so really just making combobox work like this.

[paulcpederson]

Completed