General:

BREAKING CHANGE! Changed API return and parameter type from std::tring to Arduino style String.
Renamed library name from ESP32 BLE Arduino to simple BLE.
Created a new function getFrame which returns complete data for BLEAdvertisementData::addData().
Renamed example files - removed prefix BLE_ - BLE5_ is left unchanged.
Beacon_Scanner example updated to reflect changes in API - shortened by 28 lines on TLM and URL part.
Changed UUID data type from uint16_t to BLEUUID class

Eddysstone URL:

Created a new constructor which takes as an argument a BLEAdvertisedDevice object and initializes URL data from the payload.
Created a new function BLEEddystoneURL::setSmartURL which encodes the full URL structure.

Static frame data no longer needs to be written by the user - they are initialized by the constructor.
Function BLEEddystoneURL::setPower now accepts esp_power_level_t.
Updated EddystoneURL_Beacon example to reflect changes in API - shortened by 83 lines.
Added comments with explanations to functions setData and setURL.

Tests:
EddystoneURL_Beacon with the following URLs and read them in Beacon_Scanner example and using an Android app nRF Connect for Mobile.

char unprintable[] = {0x01, 0xFF, 0xDE, 0xAD};
String URL[] = {
"http://www.espressif.com/", // prefix 0x00, suffix 0x00
"https://www.texas.gov",     // prefix 0x01, suffix 0x0D
"http://en.mapy.cz",         // prefix 0x02, no valid suffix
"https://arduino.cc",        // prefix 0x03, no valid suffix
"google.com",                // URL without specified prefix - the function will assume default prefix "http://www." = 0x00
"diginfo.tv",                // URL without specified prefix - the function will assume default prefix "http://www." = 0x00
"http://www.URLsAbove17BytesAreNotAllowed.com", // Too long URL - setSmartURL() will return 0 = ERR
String(unprintable) // Unprintable characters - setSmartURL() will return 0 = ERR

Eddystone TLM:

Created a new constructor which takes as an argument a BLEAdvertisedDevice object and initializes TLM data from the payload.
Added comments with explanations to functions setData and setVolt

TODO: test all examples if they are properly working - changes related to the String might have broken something!

Related task: #7841