Support tag(key=value) conditions in the UI

[wu-sheng]

Sub mission from #5270, the UI should provide an input box to add multiple key=value expressions to filter the traces. Ping me if you have any issue.

[wu-sheng]

UI should show a tip on the tags input

Only tags defined in the core/default/searchableTagKeys are searchable. Check more details on the Configuration Vocabulary page.

Configuration Vocabulary page should link to https://github.com/apache/skywalking/blob/master/docs/en/setup/backend/configuration-vocabulary.md