Split protected branches dropdown for scan result policy

This relates to 406826

1. Protected branches dropdown on scan result policy has to have select-all button in header instead of footer:
2. Protected branches dropdown has to be split in two dropdowns

Header should follow the rules below

• Single selection -> Choose a XXX or none
• Multiple selections -> Select XXXs

Find attached design in parent issue

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Screenshots

DESIGN

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Implementation plan

DESCRIPTION	ISSUE	MR
Update licence list dropdown	412297	TBD
Update select scanner dropdown	413016	121870
Updated protected branches dropdown	👈 This one	TBD
Show error when branches API fails and send logs to sentry	This one	TBD