Finish v3 release

[jasonpaulos]

This issue outlines all remaining work that's necessary to release v3 of this library (which is currently in development in #817)

• Bigints should be used by default for REST API decoding
• Transaction and related classes must be updated to accept bigints for all numeric fields
• Remove ability to pass raw objects as transactions to functions (tech debt, and solves Replace instanceof checks with other type check  #740)
• Update BlockHeader class to have accurate types
• Look into inline response type support in the REST API
• Should indexer responses also be typed?
• Update ESM bundle support to adhere to modern standards (Native ESM #819). For the time being, we want to continue supporting commonjs and ESM, but our ESM support has fallen behind current practices.
• Update SourceMap class to map columns (TEAL Source Map: Improve SourceMap and support columns #834)
• EncodedSignedTransaction is not properly decoded from REST API -- binary fields are typed as Uint8Array but left as base64 strings when coming from JSON

#816 has been opened as an attempt to address most of these issues

[paulmillr]

Thoughts on the security improvement? #742

It should take about 0.5-1 hour of work