Cleanup code logic

[cn0151]

What

The changes in this PR includes the following

• calling the SDK start api is now idempotent so need to check if together mode is active or not
• Remove redundant code check for screen sharing when together mode is active
• Memoize together mode properties in the video gallery utils

Why

Needed as part of together mode integration into web ui

How Tested

locally

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]

Storybook 8 URL https://60c7ae6891f0e90039d7cd54-ifuqaxnqjz.chromatic.com/

[github-actions]

Storybook 8 URL https://60c7ae6891f0e90039d7cd54-mtufpynzhz.chromatic.com/

[github-actions]

Chat bundle size is not changed.

• Current size: 1783692
• Base size: 1783692
• Diff size: 0

[github-actions]

CallWithChat bundle size is not changed.

• Current size: 12401112
• Base size: 12401112
• Diff size: 0

[github-actions]

Calling bundle size is not changed.

• Current size: 12401100
• Base size: 12401100
• Diff size: 0

[github-actions]

Storybook 8 URL https://60c7ae6891f0e90039d7cd54-rptqkycsbu.chromatic.com/

[github-actions]

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

	Lines	Statements	Functions	Branches
Base	27886 / 44346 62.88%	27886 / 44346 62.88%	783 / 1424 54.98%	2358 / 3718 63.42%
Current	27942 / 44356 62.99%	27942 / 44356 62.99%	783 / 1424 54.98%	2326 / 3704 62.79%
Diff	56 / 10 0.11%	56 / 10 0.11%	0 / 0 0%	-32 / -14 -0.63%

[github-actions]

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

	Lines	Statements	Functions	Branches
Base	56810 / 93531 60.73%	56810 / 93531 60.73%	1157 / 2670 43.33%	3508 / 5737 61.14%
Current	56811 / 93577 60.71%	56811 / 93577 60.71%	1157 / 2670 43.33%	3433 / 5696 60.27%
Diff	1 / 46 -0.02%	1 / 46 -0.02%	0 / 0 0%	-75 / -41 -0.87%