[translations] Actions & travis

[cvvergara]

Travis is taking around 16 minutes to check links in 4 languages

Move the link checking of languages to github actions as they can run in parallel, it takes less time to check the links.

How "should" it work:

• English links is always checked
• if the (last) commit message has the string [<lang>] that language links is checked

for example:

Commit msg	Action
[es] updating links	will only trigger Spanish translations link checking. (and English)
[es][de] downloading translations	will trigger Spanish & German translations link checking. (and English)
change mapserver version	will trigger only the English link checking