port: enable LG syntax in OAuthInput

[chon219]

Fixes #3306

Description

Enabled LG syntax in OAuthInput's title and text.
Fixed blocking bugs as well.

Specific Changes

• Refactored OAuthPrompt to expose sendOAuthCard()
• Updated OAuthInput to enable LG syntax
• Fixed a blocking bug in Expression.parse() to trim starting = of expressions
• Fixed a blocking bug in Templates to recognize multi line text correctly

Testing

Ported tests as well.

[coveralls]

Pull Request Test Coverage Report for Build 677436629

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 80 unchanged lines in 3 files lost coverage.
• Overall coverage increased (+0.07%) to 85.158%

---

Files with Coverage Reduction	New Missed Lines	%
libraries/botbuilder-lg/src/templates.ts	3	93.85%
libraries/botbuilder-dialogs/src/prompts/oauthPrompt.ts	24	75.79%
libraries/botbuilder-dialogs-adaptive/src/input/oauthInput.ts	53	57.19%

Totals
Change from base Build 677427736:	0.07%
Covered Lines:	18770
Relevant Lines:	21000

---

💛 - Coveralls

[joshgummersall]

One small ask, otherwise looks good.