[import] Parent and Provider improvements

[lukehoban]

Allow passing raw URN instead of name=URN for parent and provider, defaulting name to parent and provider respectively.

Report an error if the names of the parent and provider are the same (instead of silently overwriting the parent with the provider).

Provide better error messages if the provided URN is not a URN - specifically if it is a provider reference.

Fix up an error message that included a parent instead of provider URN.

Also update the help text with some additional examples.

Fixes #5958. Contributes to #10288.

[pulumi-bot]

Please view the results of the Downstream Codegen Tests Here

[pulumi-bot]

Changelog

[uncommitted] (2022-12-13)

[iwahbe]

bors r+

[bors[bot]]

Build failed:

• bors-ok

[iwahbe]

bors r+

[bors[bot]]

Build failed:

• bors-ok

[AaronFriel]

/rebase

[AaronFriel]

bors merge

[bors[bot]]

Build succeeded:

• bors-ok