feat(toastr): return toast ref

[Tibing]

Please read and mark the following check list before creating a pull request:

• I read and followed the CONTRIBUTING.md guide.
• I read and followed the New Feature Checklist guide.

Short description of what this resolves:

Closes #1008

[nnixaa]

Let's merge once we release 3.0.1

[codecov]

Codecov Report

Merging #1058 into master will decrease coverage by 0.03%.
The diff coverage is 68.42%.

@@            Coverage Diff             @@
##           master    #1058      +/-   ##
==========================================
- Coverage   76.68%   76.64%   -0.04%     
==========================================
  Files         200      200              
  Lines        6052     6059       +7     
  Branches      463      463              
==========================================
+ Hits         4641     4644       +3     
- Misses       1302     1306       +4     
  Partials      109      109

Impacted Files	Coverage Δ
...ramework/theme/components/toastr/toastr.service.ts	70.32% <68.42%> (-2.29%)	⬇️
...rc/framework/theme/components/menu/menu.service.ts	32.84% <0%> (ø)	⬆️