feat: Use retry http and add backoff

[tshe-te]

Reference: https://github.com/thousandeyes/thousandeyes-sdk-python/pull/7/files

Test locally by sending over 200 requests at the same time, which received 429s when reaching the rate limit without the change. All requests received 200 after the change was applied:

Locally terraform provider applied thousandeyes resources successfully waiting for rate limit to be reset:
Before

tshe@TSHE-M-KXTG base % terraform plan
data.thousandeyes_agent.neth_ams: Reading...

Planning failed. Terraform encountered an error while generating this plan.

╷
│ Error: 429 Too Many Requests
│ 
│   with data.thousandeyes_agent.neth_ams,
│   on example.tf line 1, in data "thousandeyes_agent" "neth_ams":
│    1: data "thousandeyes_agent" "neth_ams" {
│ 

After

tshe@TSHE-M-KXTG base % terraform plan
╷
│ Warning: Provider development overrides are in effect
│ 
│ The following provider development overrides are set in the CLI configuration:
│  - thousandeyes/thousandeyes in /Users/tshe/LocalRepo/terraform-provider-thousandeyes
│ 
│ The behavior may therefore not match any released version of the provider and applying changes may cause the
│ state to become incompatible with published releases.
╵
data.thousandeyes_agent.neth_ams: Reading...
data.thousandeyes_agent.neth_ams: Still reading... [10s elapsed]
data.thousandeyes_agent.neth_ams: Still reading... [20s elapsed]
data.thousandeyes_agent.neth_ams: Still reading... [30s elapsed]
data.thousandeyes_agent.neth_ams: Still reading... [40s elapsed]
data.thousandeyes_agent.neth_ams: Read complete after 48s [id=19]

Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with
the following symbols:
  + create

Terraform will perform the following actions:

[tshe-te]

I don't set up RetryMax so the client will attempt 5 times as the default.

[tshe-te]

This function has the same logic as the python SDK which respects Retry-After first then checks thousandeyes headers. https://github.com/thousandeyes/thousandeyes-sdk-python/pull/7/files#diff-8587054108c7902eac148f3b9ea7a213f04ddebde0be29f8b68affe61b98b39fR46

[phpinhei-te]

its ok to have ur branch with the internal ticket number, but the PR name shouldnt contain it.
prefix it with feature: since its a new feature included

Also, do you mind testing this with the terraform provider before we proceed with actually merging/tagging, etc?

[tshe-te]

@phpinhei-te Tested it locally: thousandeyes/terraform-provider-thousandeyes#265 (comment)