feature(core): allow for multiple view dirs in Express

[kiwikern]

In Express, you can set a string or an array of string as
base view paths. The views are looked up in the order they occur in
the array. The ExpressAdapter only allowed for a single string, now it
accepts an array of strings as well.

closes #1513

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
  Since this was just a typing issue, I'm not sure if this has to be tested. There was no unit test for it and since it is an express library feature it does not need to be integration tested IMO.
• Docs have been added / updated (for bug fixes / features)
  code docs only though

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: #1513

What is the new behavior?

The ExpressAdapter accepts multiple view directories.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[coveralls]

Pull Request Test Coverage Report for Build 1475

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 93.823%

---

Totals
Change from base Build 1458:	0.0%
Covered Lines:	2872
Relevant Lines:	2995

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 1475

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 93.823%

---

Totals
Change from base Build 1458:	0.0%
Covered Lines:	2872
Relevant Lines:	2995

---

💛 - Coveralls

[kamilmysliwiec]

LGTM. Thanks!

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.