Fix incorrectly assigned Vietnamese texts

[sujato]

We've been informed a number of times that some of our Vietnamese texts are incorrectly assigned, for example Puttamamsa in the Nidanasamyutta. We need to determined the extent of the problem and correct it.

In what way "incorrectly assigned"?

[sujato]

The numbers are incorrect. Leave this for now, we can look at it later.

While going over the Vietnamese numbers to make them consistent with our menu, I noticed that the numbers that are used in the AN for the filenames differ from the ones in the title tag. The numbers used for the file names are supposedly the numbers as used in SC and the ones in the title tag the alternative numbers (as from legacy site: AN 3.103 [AN 3.101a]).

For the sn12.63 Puttamamsa however there is no alternative number and the number 63 was provided by the translator when the files were made. In fact, the heading says <h1>63. Thịt Ðứa Con: <span lang="pli">Puttamaṃsūpama</span></h1> so it seems indeed the right number.
I ran the whole sutta through Google Translate, which actually came out as reasonably readable and showed that it is indeed the correct sutta; it has the simile of the couple with the beloved child.

SN54.21 is definitely wrong because it does not exist. (See https://legacy.suttacentral.net/vn/sn54.21). I've now added this text to the bottom of sn54.20 where it belongs, but the original sn54.20 is still there too so that needs to be sorted.

Same with SN49.55, SN47.105, sn50.111, sn46.203

Another weird inconsistency with many non-existent numbers:
sn43.49, sn43.57, sn43.58, sn43.103, sn43.104, sn43.149, sn43.150, sn43.151. I've grouped all of these under sn43.44 for the time being.
sn45.181, sn45.182, sn45.183, sn45.184, sn45.185 I have grouped under sn45.180

In sn46 the numbering is very confusing.

[sujato]

See also vi/pli/sutta/sn/sn53/sn53.45-54.html

[aminah-sc]

Hopefully, this has been fixed with the html5 upgrade and will be on the site following the completion of suttacentral/suttacentral#1491. However, as this work has been done by Google Translate and inference it should be double-checked by a Vietnamese speaker. See here for volunteer: https://discourse.suttacentral.net/t/fixing-html-on-legacy-texts/11242/52?u=aminah