Berry int64 added low32() and high32() methods, used in Matter

[s-hadinger]

Description:

Berry int64 class has now low32() and high32() to get the low/high 32 bits as native int, without allocating any new object. This is used to encode 64 bits int as bytes.

var i64 = int64.fromstring("1234605616436508552")   # 0x1122334455667788
print(i64.high32())
# 287454020 = 0x11223344
print(i64.low32())
# 1432778632 = 0x55667788

Checklist:

• The pull request is done against the latest development branch
• Only relevant files were touched
• Only one feature/fix was added per PR and the code change compiles without warnings
• The code change is tested and works with Tasmota core ESP8266 V.2.7.7
• The code change is tested and works with Tasmota core ESP32 V.3.0.2
• I accept the CLA.

NOTE: The code change must pass CI tests. Your PR cannot be merged unless tests pass