RPCConsole: Throw when overflowing size_t type for array indices

[maflcko]

To test:

-> getblock(getbestblockhash(), 1)[tx][22222222222222222222222222222]

Before:

<- 868693731dea69a197c13c2cfaa41c9f78fcdeb8ab8e9f8cdf2c9025147ee7d1 (hash of the coinbase tx)

After:

<- Error: Invalid result query

[jarolrod]

concept ack

[jarolrod]

ACK faa5e17

tested and code review ack. This is a nice catch!

on master:

<-  getblock(getbestblockhash(), 1)[tx][22222222222222222222222222222]
->  e3038545d5b68dc61a282f15eb8e3ffbfb50c3f9955380a1fde3c1c858414d38

on PR branch:

<-  getblock(getbestblockhash(), 1)[tx][22222222222222222222222222222]
->  Error: Invalid result query

[shaavan]

ACK faa5e17
Tested on Ubuntu 20.04

This PR allows displaying runtime error for inputs greater than the limit of size_t type.

This is done by using the ToIntegral<size_t> function, which will check the size of the input argument. Earlier, the logic was to check if each character of the input argument is a digit or not without considering the overall length of the input argument.

This is undoubtedly an improvement over the current Master, and I agree with this PR. I am adding the screenshot of input and outputs that I used to test this PR on the GUI console. The test was done on the Signet network.

Screenshots:

Master (outputs null, without errors)	PR (output error)