Making "updateText" to be public

[themoonrat]

We often give advice to use this to force updating of the texture outside of a render cycle; for example, to generate a texture containing a piece of text which is then shared across multiple sprites.

For example
#5138 (comment)
#5043 (comment)
https://www.html5gamedevs.com/topic/42319-pixitext-caching-with-resolution/?do=findComment&comment=239720

• Tests and/or benchmarks are included
• Documentation is changed or added
• Lint process passed (npm run lint)
• Tests passed (npm run test)

[codecov-io]

Codecov Report

Merging #6425 into dev will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##              dev    #6425   +/-   ##
=======================================
  Coverage   78.33%   78.33%           
=======================================
  Files          57       57           
  Lines        2820     2820           
=======================================
  Hits         2209     2209           
  Misses        611      611

---

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 ff77311...0462811. Read the comment docs.