refactor(pdl): convert all pdsc to pdl

[mars-lan]

Use the automated tool in https://linkedin.github.io/rest.li/pdl_migration
Also update all relevant docs

Checklist

• The PR conforms to DataHub's Contributing Guideline (particularly Commit Message Format)
• Links to related issues (if applicable)
• Tests for the changes have been added/updated (if applicable)
• Docs related to the changes have been added/updated (if applicable)

[jywadhwani]

There are some more md files that reference the PDSC models https://github.com/linkedin/datahub/search?p=1&q=pdsc&unscoped_q=pdsc
We can include them in this commit, or address them in the next one.

[jywadhwani]

Looks like you just pushed another commit that addresses my comment :)

[mars-lan]

Yeah did a more thorough search after my initial commit. Maybe we should cut a 0.3.2 release before making this big change @jywadhwani?

[jywadhwani]

The original plan was to cut release 0.3.2 and then include PDL changes. We might have to wait till sometime next week for 0.3.2 release to be out (before the town hall) - I will leave it to you to decide whether to push this change now @mars-lan.

[mars-lan]

Is there any additional changes planned for 0.3.2? If not, I push first this and let you cut a release based off the preceding commit next week?

[jywadhwani]

No additional changes needed for 0.3.2. We can cut a release next week based off the preceding commit. You can ship this one!