Decompiler: Fix inlining for call_return override

[LukeSerne]

Previously, when decompiling a function with a call to an inlined function that is the result of a call_return flow override, the inline would fail with a Return address prevents inlining here warning. This was due to an overly restrictive check in
FlowInfo::testHardInlineRestrictions. With this PR applied, these function calls are inlined again.

This PR also allows CALL pcode-ops in EZ model functions, since CALL operations don't end basic blocks. This also significantly improves Ghidra's ability to inline functions with function calls inside (such as those generated by the call_return override).

This PR also makes the warning more explicit on why the return address prevents inlining.

Sample
FUN_a7d3fb00_ret_addr_prevents_inline.xml (manually edited to ensure the flow overrides are assigned to the correct function).

Before
Decompiler output without this PR applied:

/* WARNING: This is an inlined function */

void FUN_a7d3fb00(undefined4 *param_1) {
  param_1[0x1c] = 0;
  memset(param_1 + 0x1e,0,800);
  *param_1 = 0;
                    /* WARNING: Return address prevents inlining here */
  FUN_a7d42a0c(param_1 + 1);
  return;
}

After
Decompiler output with this PR applied:

/* WARNING: This is an inlined function */
/* WARNING: Inlined function: FUN_a7d42a0c */

void FUN_a7d3fb00(undefined4 *param_1) {
  param_1[0x1c] = 0;
  memset(param_1 + 0x1e,0,800);
  *param_1 = 0;
  memset(param_1 + 1,0,0x6c);
  return;
}