Read receipts selector fix

[mgamis-msft]

What

1. Change type return of getReadReceipt base selector
2. Avoid potentially calling filter when readReceipts is undefined

Why

When I initialize a new chat adapter for my breakout rooms feature I get this error:

How Tested

Fixed the above error with fix.

Process & policy checklist

• I have updated the project documentation to reflect my changes if necessary.
• I have read the CONTRIBUTING documentation.

Is this a breaking change?

• This change causes current functionality to break.

[github-actions]

Chat bundle size is increased❗.

• Current size: 2109616
• Base size: 2109613
• Diff size: 3

[github-actions]

CallWithChat bundle size is increased❗.

• Current size: 6417868
• Base size: 6417865
• Diff size: 3

[github-actions]

Calling bundle size is not changed.

• Current size: 5055987
• Base size: 5055987
• Diff size: 0

[github-actions]

@azure/communication-react jest test coverage for stable.

	Lines	Statements	Functions	Branches
Base	26330 / 42239 62.33%	26330 / 42239 62.33%	723 / 1309 55.23%	2085 / 3336 62.5%
Current	26385 / 42239 62.46%	26385 / 42239 62.46%	723 / 1309 55.23%	2096 / 3349 62.58%
Diff	55 / 0 0.13%	55 / 0 0.13%	0 / 0 0%	11 / 13 0.08%

[github-actions]

@azure/communication-react jest test coverage for beta.

	Lines	Statements	Functions	Branches
Base	53526 / 87407 61.23%	53526 / 87407 61.23%	1078 / 2440 44.18%	3139 / 5211 60.23%
Current	53571 / 87410 61.28%	53571 / 87410 61.28%	1078 / 2440 44.18%	3179 / 5243 60.63%
Diff	45 / 3 0.05%	45 / 3 0.05%	0 / 0 0%	40 / 32 0.4%