add terraform charm and product module

[Thanhphan1147]

Add terraform module to deploy haproxy, together with hacluster and grafana-agent

Checklist

• The charm style guide was applied
• The contributing guide was applied
• The changes are compliant with ISD054 - Managing Charm Complexity
• The documentation is generated using src-docs
• The documentation for charmhub is updated
• The PR is tagged with appropriate label (urgent, trivial, complex)

[github-actions]

license-eye has checked 90 files.

Valid	Invalid	Ignored	Fixed
40	3	47	0

Click to see the invalid file list

• terraform/charm/main.tf
• terraform/charm/outputs.tf
• terraform/charm/variables.tf

Use this command to fix any missing license headers

```bash

docker run -it --rm -v $(pwd):/github/workspace apache/skywalking-eyes header fix

</details>

[github-actions]

Test results for commit 667439e

Test coverage for 667439e

Name                         Stmts   Miss Branch BrPart  Cover   Missing
------------------------------------------------------------------------
src/charm.py                   208     85     56      8    52%   87, 163, 171-184, 189, 194, 204, 223-245, 249-271, 282-283, 311-316, 323, 336-342, 348, 351, 358, 370-384, 389-392, 397, 405-420, 429-435
src/haproxy.py                  70     19      2      1    72%   75, 92-97, 112-119, 132-140, 148-154, 163-172, 182-183, 211
src/http_interface.py           73     25      4      0    62%   74, 83, 92, 106-108, 126, 138, 150, 162, 170-175, 187, 194, 202, 217-227
src/state/config.py             41     12      6      3    68%   53, 60-62, 67-68, 71, 93-95, 107-108
src/state/exception.py           1      0      0      0   100%
src/state/ha.py                 30      1      2      1    94%   50
src/state/haproxy_route.py      98     15     24      4    80%   102, 118, 141-145, 159-167, 215, 251, 259
src/state/ingress.py            35      0      4      0   100%
src/state/tls.py                38      5      8      3    83%   69, 72-73, 109-110
src/state/validation.py         38     16      6      1    52%   65-66, 70-83
src/tls_relation.py             48      8     18      7    77%   60, 62, 64, 74-75, 77->76, 100-106, 118->120
------------------------------------------------------------------------
TOTAL                          680    186    130     28    68%

Static code analysis report

Run started:2025-05-26 21:19:16.036606

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 3024
  Total lines skipped (#nosec): 1
  Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 2

Run metrics:
  Total issues (by severity):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
  Total issues (by confidence):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
Files skipped (0):