refactor: insert option

[alexander-akait]

This PR contains a:

• bugfix
• new feature
• code refactor
• test update
• typo fix
• metadata update

Motivation / Use-Case

Implement insert option for custom insert logic

Breaking Changes

Yes

BREAKING CHANGE: insertAt and insertInto option was removed in favor insert option (please look docs and examples)

Additional Info

We still doesn't recommended use non standard behavior

[codecov]

Codecov Report

Merging #413 into master will increase coverage by 2.38%.
The diff coverage is 100%.

@@           Coverage Diff            @@
##           master   #413      +/-   ##
========================================
+ Coverage   97.61%   100%   +2.38%     
========================================
  Files           3      3              
  Lines         210    200      -10     
  Branches       71     72       +1     
========================================
- Hits          205    200       -5     
+ Misses          4      0       -4     
+ Partials        1      0       -1

Impacted Files	Coverage Δ
src/runtime/injectStylesIntoStyleTag.js	100% <100%> (+0.62%)	⬆️
src/index.js	100% <100%> (ø)	⬆️
src/runtime/injectStylesIntoLinkTag.js	100% <100%> (+20%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b7ed255...21f030c. Read the comment docs.