Removes a few Warnings and fixes Math rand() to work like Arduino mainstream

[SuGlider]

Description of Change

This is part of a work to clean up Warnings from the core. The flags below are not necessary anymore:

-Wno-frame-address 
-Wno-error=unused-function 
-Wno-error=unused-variable 
-Wno-error=deprecated-declarations 
-Wno-sign-compare 
-Wwrite-strings
-Wno-error=unused-but-set-variable 
-Wno-old-style-declaration

But we still need -Wno-unused-parameter because IDF inline declarations use some parameters that are not used dependening on #define

This PR also fixes Math rand(negative parameter) in order to make it work exactly as it does in Arduino mainstream.

  Serial.println("random(-5) ::");
  for (uint8_t i = 0; i < 10; i++) {
  Serial.print(random(-5));
  Serial.print(" | ");
  }
  Serial.println();

  Serial.println("random(-3, 3) ::");
  for (uint8_t i = 0; i < 10; i++) {
  Serial.print(random(-3, 3));
  Serial.print(" | ");
  }
  Serial.println();

Tests scenarios

Tested with ESP32 WROVER-E, using a modified platform.txt with this change:

compiler.c.flags.esp32=-Wno-unused-parameter -mlongcalls -ffunction-sections -fdata-sections -ggdb -freorder-blocks -fstack-protector -fstrict-volatile-bitfields -fno-jump-tables -fno-tree-switch-conversion -std=gnu99  -MMD -c

compiler.cpp.flags.esp32=-Wno-unused-parameter -mlongcalls -ffunction-sections -fdata-sections -ggdb -freorder-blocks -fstack-protector -fstrict-volatile-bitfields -fno-jump-tables -fno-tree-switch-conversion -std=gnu++11 -fexceptions -fno-rtti  -MMD -c

Related links

It is a pre requisite for merging #7060