feat(datepicker): add greek language translation (#5575)

[dimitrismitsiou]

Add el - greek support

PR Checklist

Before creating new PR, please take a look at checklist below to make sure that you've done everything that needs to be done before we can merge it.

• read and followed the CONTRIBUTING.md guide.
• built and tested the changes locally.
• added/updated tests.
• added/updated API documentation.
• added/updated demos.

[codecov]

Codecov Report

Merging #5737 (92394f3) into development (c0beddb) will decrease coverage by 0.03%.
The diff coverage is n/a.

@@               Coverage Diff               @@
##           development    #5737      +/-   ##
===============================================
- Coverage        77.55%   77.51%   -0.04%     
===============================================
  Files              302      302              
  Lines            10549    10549              
  Branches          2583     2583              
===============================================
- Hits              8181     8177       -4     
- Misses            2358     2362       +4     
  Partials            10       10              

Impacted Files	Coverage Δ
src/chronos/i18n/pl.ts	85.00% <0.00%> (-3.34%)	⬇️
src/chronos/i18n/sk.ts	85.13% <0.00%> (-1.36%)	⬇️
src/chronos/i18n/cs.ts	87.64% <0.00%> (-1.13%)	⬇️

---

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 c0beddb...92394f3. Read the comment docs.

[daniloff200]

@dimitrismitsiou thanks for the contribution!
I will review this PR tomorrow :)

[daniloff200]

In general, looks good, but, you have to import that to the module, to the locale.ts file , and, of course, we need a unit tests for it

Check these PRs, to see, how it should look, as an examples:

https://github.com/valor-software/ngx-bootstrap/pull/5685/files
https://github.com/valor-software/ngx-bootstrap/pull/5556/files
https://github.com/valor-software/ngx-bootstrap/pull/4812/files
https://github.com/valor-software/ngx-bootstrap/pull/5551/files

[cypress]

---

Test summary

87 • 0 • 6 • 0

---

Run details

Project	ngx-bootstrap
Status	Passed
Commit	e3e5ad7 ℹ️
Started	Jul 29, 2021 9:01 PM
Ended	Jul 29, 2021 9:05 PM
Duration	04:40 💡
OS	Linux Ubuntu - 20.04
Browser	Electron 87

View run in Cypress Dashboard ➡️

---

This comment has been generated by cypress-bot as a result of this project's GitHub integration settings. You can manage this integration in this project's settings in the Cypress Dashboard