Phrase list definition keyword should be case insensitive

[feich-ms]

Versions

4.11.1

Describe the bug

When defining phrase list in lu file, the case is sensitive for phraseList. For exmaple,
@ phraseList ticket(interchangeable) = will fail, but
@ phraselist ticket(interchangeable) = will work

To Reproduce

Steps to reproduce the behavior:

1. Create phrase list definition in lu file with phraseList key word.
2. Publish it with luis build cmd.
3. You will see the exception.

Expected behavior

phraseList should also be recognized as key word

Screenshots

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Additional context

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[bug]