Provide hints to fill in usernames in build feature

[dtretyakov]

Currently it requires manually typing usernames for default assignee and list of exclude users which could be automated by TeamCity magic button like that:

[rugpanov]

@dtretyakov comment:

we can use <bs:projectData /> to write ProjectDataFetcher

https://github.com/JetBrains/teamcity-bazel-plugin/blob/f4c50ae09bf546411a9e5cb89ab7b5885dfa57e7/plugin-bazel-server/src/main/resources/buildServerResources/editBazelParameters.jsp#L82-L84
https://github.com/JetBrains/teamcity-bazel-plugin/blob/f4c50ae09bf546411a9e5cb89ab7b5885dfa57e7/plugin-bazel-server/src/main/kotlin/jetbrains/buildServer/bazel/fetchers/BazelCommandFetcher.kt

(Here is an examples of selection mode single/multiple for default/exclude list options)

[rugpanov]

Implemented and then reverted at build #44.
It seems such element can confuse users and slow down the performance.
So it was decided not to implement for now.

[dtretyakov]

But we could leave it open until it will be resolved.