Better error handling for compilation exceptions in .yml files

[drewbanin]

Describe the bug

A malformed yml file can result in an error like:

Instead, this error should include information about the file in which the errant jinja code was found.

Steps To Reproduce

Create a .yml file with the contents:

version: 2

models:
  - name: debug
    meta:
      abc: 123

      columns:
        - name: id
          description: '{{ doc("mydoc") }}'

Note that the columns entry is errantly indented under meta.

Run dbt ls or dbt compile to see the compilation exception.

Expected behavior

I would expect to see the filename containing the errant code in the raised exception.

The output of dbt --version:

v0.17.0-rc3

[drewbanin]

closed in #2501