Progress indication for schematics

[devversion]

Since the TSLintFixTask can take a lot of time (e.g. if used to apply source code transformations for ng-update), it would be nice to have a progress indicator that shows that "something" actually runs.

For example: if someone runs ng update @angular/material@next, it's not clear for a period of time that the fix task actually "runs". See: angular/components#12774.

An option that can be specified when configuring the TSlintFixTask would be nice to have. The option would then show a simple progress indicator while TSLint runs.

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Ideally there would be a way for a schematic to:

• Have an progress-spinner with a name of the schematic currently running
• Report a status (similar to how Bazel repository_ctx can report statuses)

Nowadays a lot of schematics need to run as part of an ng update and it would be helpful to know what schematic currently runs / what it currently does (if known)

cc. @jelbourn

[Splaktar]

Note that while having the ability to indicate a % complete would be nice in some cases, in the general case, it's most important to just be able to indicate that schematic X is currently running.

With Angular version 8, some of my schematics for core, CLI, and material/cdk were taking 10+ minutes to complete, but it seemed like they were hung/unresponsive. This is bad DX.

[devversion]

Totally agree. Thanks for adding that!

[alan-agius4]

Also tracked internally in http://b/188066584.