Berry added f-strings as an alternative to string formatting

[s-hadinger]

Description:

Berry add support for f-strings (similar to python). f-strings are converted internally by lexer to their format equivalent and then parsed as normally. It works as a transpiler, syntactically rewriting code before parsing.

Principle:
f"begin { <expr> : <format>} end" becomes format("begin %<format> end", expr

Example:
f"2 + 2 equals {2+2:i}" becomes format("2 + 2 equals %i", 2+2)

If the format is unspecified, %s is inserted:
f'"foo" + "bar" equals {"foo"+"bar"} becomes format("\"foo\" + \"bar\" equals %s", "foo"+bar")

If you accidentally insert % in the format, it is ignored:
f"1/3 equals {1.0 / 3.0 :%.3f}" becomes format("1/3 equals %.3f", 1.0 / 3.0)

To output { use double brackets: (note that % are automatically doubled)
f"{{ 1% }}" becomes format("{ 1%% }")

Use the = (equal sign) to also output the expression:
f"{id=:i} {name=}" becomes format("id=%i name=%s", id, name)

Note: f-strings takes less than 1KB of flash memory in the lexer

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.2.7.4.9
• The code change is tested and works with Tasmota core ESP32 V.2.0.10
• I accept the CLA.

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

[barbudor]

Berry is more and more pythonic 🤣
Next step, remove end 😵‍💫

[s-hadinger]

Nah...