add new param DisableSiteBranding for Set-SPOSite command

[RongqiZ]

We want to disable site branding in site collection level, so added a new param DisableSiteBranding to the Set-SPOSite

[learn-build-service-prod]

Learn Build status updates of commit 21ad264:

✅ Validation status: passed

File	Status	Preview URL	Details
sharepoint/sharepoint-ps/Microsoft.Online.SharePoint.PowerShell/Set-SPOSite.md	✅Succeeded	View (sharepoint-ps)

For more details, please refer to the build report.

[learn-build-service-prod]

Learn Build status updates of commit ecf3646:

✅ Validation status: passed

File	Status	Preview URL	Details
sharepoint/sharepoint-ps/Microsoft.Online.SharePoint.PowerShell/Set-SPOSite.md	✅Succeeded	View (sharepoint-ps)

For more details, please refer to the build report.

[samkabue]