Allow to select any country as comparison group

[luizaandrade]

• the "focus country" cannot be in the comparison group
• show group of countries (WB regions and OECD group) first and then all countries one by one
• if select WB regions or OECD, select all countries in that group and show that in the display (so user may choose countries to drop)
• force to select min 10 countries in the comparison group

[luizaandrade]

the notes will need to be updated to reflect the countries selected

[luizaandrade]

Country groups are coming from this source: https://datahelpdesk.worldbank.org/knowledgebase/articles/906519-world-bank-country-and-lending-groups

[luizaandrade]

To-do

• [x] Add notes on definition of country groups @luizaandrade
• [x] Remove selected base country from list of selected comparison countries @luizaandrade
• [x] Add toggle code for "apply selection" button so at least 10 countries need to be selected @luizaandrade
• [x] Update percentiles to use selected countries @gabrielvazdemelo
• [x] Allow for data table to use only selected comparison groups (low priority) @luizaandrade