Update i18n docs to reflect v7 changes

[mwistrand]

Type: feature

The following has been addressed in the PR:

• There is a related issue
• All code has been formatted with prettier as per the readme code style guidelines
• Unit or Functional tests are included in the PR

Description:

Resolves #698

Unfortunately, as I cannot read Chinese, the corresponding zh-CN docs are left untouched.

• Replace references of the old i18n function with localizeBundle().
• Remove references to CLDR data as these data are now injected at build time.
• Remove references to setLocaleMessages and getCachedMessages.
• Replace message formatter examples with format examples.
• Update documentation on reading the current locale.

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[codecov]

Codecov Report

Merging #705 into master will not change coverage by %.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #705   +/-   ##
=======================================
  Coverage   97.76%   97.76%           
=======================================
  Files         119      119           
  Lines        6929     6929           
  Branches     1573     1573           
=======================================
  Hits         6774     6774           
  Misses        155      155           

Impacted Files	Coverage Δ
src/i18n/i18n.ts	98.90% <ø> (ø)

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[xiaohulu]

@mwistrand I will update zh-CN docs.

[agubler]

@mwistrand Do you think we need to keep a section on the build tooling? Covering the locale and supportedLocales options, as this is what is used to automatically inject the required CLDR data?

[mwistrand]

@agubler There is already a "Configuring supported application locales" section beneath the top-level "Internationalizing a Dojo application" page that describes the locale and supportedLocales values in the .dojorc.

[agubler]

Should we mention on that page that without the locale then i18n will only use root bundles and do non icu message formatting? Or do we think that's enough?

[mwistrand]

That's not a bad idea. I'll update to include that warning.