[PORT]Loose grammar to make Structure LG more torren

[Danieladu]

Close: #1973

1. Support newline in structure lg content

> this is executable
# template
[Activity
  text = hi

 speak = hi
]

2. Add more catchable errors
   for example:

# template
[Activity]
- hi

Originally, it would throw a syntax error, but now, some readable errors would be thrown.

[coveralls]

Pull Request Test Coverage Report for Build 117121

• 16 of 17 (94.12%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.02%) to 81.5%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
libraries/adaptive-expressions/src/parser/expressionParser.ts	1	2	50.0%

Totals
Change from base Build 117115:	0.02%
Covered Lines:	9341
Relevant Lines:	11042

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💛 - Coveralls